I have been thinking something recently like how people in fanfiction or even in Naruto series doesn't use chakra to it's full potential i mean what is chakra ? It is a amalgum or combination of mental energy and physical energy . Why people like Uchiha ,Senju etch have large chakra eeserve that is because there body is formed like that which naturally inclined toward gaining larger chakra reserve , i know now yoi guy's will ask how so let me explain first . What are senju clan know for ?
Well they are know for strong body and partial regenration and Uzumaki clan know for high regenration , these clan are from asura bloodline thus they inherit sage of six path body that why they already possess high physical energy and with time as well as practice they acquir mental energy .Thus they have high chakra ,where as uchiha clan have dojutsu which only unlock when they face certain crisis which bring change in there mantality or goes against there will thus strengthing mental energy and with time they get increase physical energy with continuos
hard work thus they have high chakra .
know we discuss about other clan as we have read in genetic there are certain charachter which depend on our environment
like we can say height , some people inherit short height from their parent but if they know they are going to have short height even after becoming adult they change there diet as well as do certain exercise to become taller and i have seen many whose parent are below 5'6 and they have height around 5'8 .Thus environment effect people , when chakra was introduced it was used by many but due to increase in struggle for survival like in time of waring state era where people are at constant war they adapt by continuos struggle which condition there mind and body increaseing there chakra reserve and with passage of time it led to formation of clan as people of clan start reapecting there bloodline more , so that how normal civilian become ninja and form clan .
Let's discuss about how normal civilian can increase chakra in there body. It is easy as well as hard , what they need is strict schedule of training in which they meditate for mind and exercise for body . What i have come to conclusion is that to manupilate chakra we requir mental energy thus people with EM sharingan can form susano as it could gave people very large amount of mental strain to even form inner organ like rib cage and othwr framework thus if person want to form susano without sharingan he need all needed information about internal body and imaginative power to form various shape . That why mental energy in chakra is necessary , person can increase there mental energy by forming various complex shape like we can start with triangle than to more hard shape which can increase mental energy of person Tobiram senju is know for doing water dragon jutsu with 1 hand sign it is due his brain get adepted in forming dragon shape with how many time he have used it ,usually water dragon jutsu take 44 hand sign and it take unadept person 1- 2 minute to for forming hand sign . Only jonin like kakashi can form 44 hand sign in 1 second .So conclusion mental energy can be trained and increase by following way -
1) shape manupilation practice more you practice better it is ,try forming various shapes.
2) Rasengan can be said as peak of shape and chakra manupilation .
3) Person can increase mental energy by being smart or study hard like sakura was born with high IQ though i hate her but no particuler reason for that .
4) Through meditation one can increase mental energy.
But here come second part that is physical part of chakra or physical energy which can only be increase with hard work and training best way is to nourish your body with chakra or use various modern body building techniqui like replacing pink muscle in your whole body etc .