Hello SIDDHARTH2900,
Vitality can go up to 130% and can't go down below 80%, to make Vitality go up you need to sell any drugs and fulfill their Quota.
Every Quota you fill up gives you 5% Vitality, you lose 1% Vitality per Hour even if you're not online, so you need to Sell Drugs Everyday to get your Vitality up.
If your Vitality is over 100% it will give you additional % increase on money you earn in Mines same with tokens and crystals.
Vitality 101% gives you 1% increase, 102% gives you 2% increase and so on until 130%.
Hope this Helps you.