What doesn't kill you makes you stronger

Yeah i got like chains and charms and all of that in my hair, now when i put em in, they dont hurt for a few days, and after that, any additional pulling hurts, so then i take it out and wait til it stops hurting and put it back in, and repeat, so i was wondering if the 'what doesn't kill you makes you stronger ' thing applied to hair strength, are those hairs becoming stronger or just healing, because everytime i put back in, it seems like it doesn;t hurt nearly as bad...maybe its just me, but then again, youd think that as hair grew longer it would weigh more and eventually be so heavy youre in aching pain, but from what ive heard, its not like that, maybe hair is just like muscle, what makes muscles grow is the breaking down from working out and the natural overbuilding, so yeah im kinda of just going of now, but am i right on it being a universal thing