You can have only one of two pains in life: the pain of discipline or the pain of regret. And only one will lead to transcendence of the spirit, while the other leads to a kind of spiritual suicide.
If you want more happiness in life, find a deeper meaning, a richness, and a connection to everything and everyone around you.
If you want more strength, turn your wounds into your wisdom and your pain into your purpose. Do that, and you will never have to look for strength again. Strength will find you.