AN: Hi all, this is my very first fanfiction so please be nice. This story came about as a combination of reading way too much Naruto fanfiction and some ideas I had based around the show and manga. Particularly how focused and balanced as a person Naruto becomes later in life. So enjoy.
In hindsight Naruto realised that his main problem throughout his life was control. Primarily chakra control.
Born as an Uzumaki, Naruto naturally had an abnormally high chakra reserve, chakra being the combination of physical and mental energy. In addition to this Naruto also had the unfortunate fate of becoming a jinchuuriki moments after his birth. Being the last Uzumaki, and as only an Uzumaki could hold the massive force of chakra that is the nine tailed fox, there was little choice but to seal the beast within him. Which resulted in Naruto gaining the not inconsiderable chakra reserves of a biju on top of his already large natural reserves.
If that wasn't enough the nature of the seal placed upon him also contributed to his fundamental difficulty in control. As the seal itself used Naruto's chakra to process and filter the chakra of the fox throughout the day, only to pump the purified charkra back into Naruto each morning as the sun rose. Meaning that any control he gained was compromised as his reserves grew day by day. As such, where other shinobi's chakra flowed throughout their bodies in a steady stream, Naruto's chakra was always in a state of flux.
The defining principle of chakra control means that as chakra is used, not only control is gained but the chakra reserves themselves grow as the mind and body become more harmonised. Unfortunately for Naruto his body was always out of balance with the enormity of his chakra reserves as you would expect if you had a toddler with the power of a chunin. The result of this was that by the time Naruto was twelve his reserves rivaled a Kage's but his control was almost non-existant.
Uzumaki children, due to their naturally higher than average reserves, traditionally started chakra training as soon as they were potty trained to make sure that their minds and bodies developed as one. Being the last of the Uzumakis meant there was no-one to carry on this tradition with Naruto and so when he finally learnt the basics of control in the academy with the other children, he was drastically out of his depth. Where most his fellow academy student's chakra trickled through their systems, Naruto's chakra gushed, spilling out and around him forming an invisible chakra cloud.
When Naruto was eight his chakra reserves were so vast that his chakra signature blanketed much of the village, as such to most of the chakra sensors living within the village Naruto was background noise. Incidentally this was the secret to how Naruto managed to escape from Jonin and Anbu after completing his pranks. To most sensors it was like trying to find an open tap at the bottom of a lake. Despite popular belief, even Iruka-sensei could not sense Naruto, the reason he could always find Naruto when others could not was due to his own history as a prankster. Iruka would simply trace the chase through the village then head to the nearest relatively safe hiding spot and there Naruto would be.
Later in life, this chakra cloud would become as even greater asset as no-one could pinpoint his location through his chakra unless he was using it. Where other shinobi hid their presence by making their reserves as small as possible, Naruto simply blanketed the whole region. Due to his underwhelming physical appearance, enemy shinobi assumed the chakra cloud to be a product of the Jonin or Sannin that accompanied him whenever he left the village and so he remained largely underestimated for much of his life.
Having large chakra reserves by itself is no great problem as it increases stamina, fighting power and accelerates healing exponentially, however without control it could also have a really detrimental effect upon the mental and physical development of a young person, especially if the body itself is neglected.
Because of his status as a Jinchiriki, Naruto did not receive the best upbringing. Sure he received the basics of survival, but that was all he received. As such his mind and body did not develop in balance with his chakra growth. Chakra need an outlet, it can not simply disipate as it wants to be used. Some of his chakra went to the fox to replenish that lost in the sealing process, and some went to maintaining his own body as his healing factor tried to counterbalance the effects of malnutrition. But that still left a large amount of chakra constantly circulating through Naruto's small body.
This excess chakra manifested in hyperactive behaviour and an overloaded thinking process. As a result of this by the age of six it was physically impossible for Naruto the stay still, when forced to try as a punishment for bad behaviour he would actually vibrate with supressed energy. His mind, much like his body, was also in a state of constant motion flitting from one thought to the next, so that his attention span ended up as that of a goldfish. It was only when his mind and body worked as one that he could focus and only then by repeating the same action to exhaustion, which explains his love of training as it not only fulfilled a physical need but allowed his mind to rest. As such the academy was possibly the worst learning environment for Naruto as he was a kinetic learner and the stagnant environment of the academy caused his development to atrophy.
It was only when he learnt the shadow clone technique that Naruto's development as a ninja could finally begin as splitting his chakra amongst the clones balanced out his energies and allowed his mind to slow down enough that he could retain knowledge. Naruto never noticed the memory transference that was a by product of the shadow clone jutsu, not from any lack of real intelligence but simply as an indication of the normal state of Naruto's mind. The hyperactive nature of Naruto's thinking process meant that he often thought multiple thoughts all at once as his chakra enhanced mind was in an almost constant overload of information as he examined each idea from multiple angles.
A by-product of this meant that Naruto was incapable of sustained anger, as he could see all points of view at once, but it also meant that he found it difficult to focus as his mind constantly went off on tangents of stray thought. But in situations of survival, when adrenaline coursed through his veins, it was this ability to absorb vast amounts of data all as once that resulted in his often startlingly ingenious plans, especially after he could split the responsibility of response to stimuli amongst his shadow clones. Unfortunately as Naruto's chakra induced hyperactivity was present almost from the time he learnt to walk, no-one in the village noticed why he acted like he did and so it wasn't until Naruto's training journey with Jiraiya and the constant chakra control exercises and usage that this entailed that Naruto's true personality and potential could be realised as his mind and body finally became somewhat balanced.
Learning the Rasengan was perhaps the best thing that could have happened for Naruto's development as a ninja. The chakra heavy technique not only used up a large quantity of the excess chakra circulating through his body, but the very nature of the technique as a highly advanced chakra control technique was possibly the only control technique that could have made a dent in his vast reserves, as it dealt with the physical manipulation of chakra energy. This technique in conjunction with the shadow clone technique gave Naruto the relative control of an academy student and finally allowed Naruto to show the serious and focused shinobi he was always capable of becoming.
Yes, Naruto's main problem growing up was chakra control. Perhaps now that he found himself inexplicably five years old again he might finally be able to achieve it.