Make sure your shoulders, head, and back are all in contact with the surface youβre sitting on, ofc your head can be slightly slouched + I have had genuinely the most disgusting posture ever and another helpful thing is to have someone take a picture or video of you walking and it will make you hate yourself so badly that you become so ashamed and your body will hopefully naturally correct itself.
Yoga is def a best place to start...........there's this starting basic 12 forms called SUN SALUTATIONS..........12 moves........half of them repeats so no worries...........thats the level 1 of it and slowly increase the repetitions like first day only one reap of salutations........to 3 reaps of salutations to 6 reaps after 2 weeks and u'll already start seeing ur back being lighter on Day 3..........MOST IMP OF ALL------BREATH WORK...........know when to breathe and when to release in that between movements of 12(since its a cycle form).........later on u can try advanced moves but this is enough for starting.............pls make sure breathe work is absolutely right like when bending down releasing out etc etc
https://www.arhantayoga.org/sun-salutation-surya-namaskara/ this one is the most detailed crt pattern one
https://harithayogshala.com/blog/steps-of-surya-namaskar ......this has extra 3-4 poses that's necessary......sry for the overload info

Someone pls tell me how do i correct my posture I've become shrimp my backbone has got curved from sitting and bending downwards ( i can't go to gym so don't tell me to go gym as im not allowed to) tell me exercises yoga anything