Shoulder dislocation keeps happening.. how do i prevent next one?

i first got my shoulder dislocated while playin some unprotective tackle football @ the park, but when it pop'd out, my friend pulled it and put it back in place, then i kept playin thinking it was nothing, then after the game i started to rotate it , thinking it would help it, but it dislocated again while i was stretchin it, then after that incident, i dislocated it again at work while climbing up on the roof, saw the doctor and said its torn ligament or something but he said i should just rest it and not do anything, then a few months after that, i dislocated it again while workin out at the gym ( i was doing some pull ups, then i switched to doing the machine where u are doing butterflies with ur arm to work ur chest and thats when it hurt the most, . my questioin is how do i train my shoulder now since its been through so much so that it strenghtens and wont dislocate again? i really am motivated to lift weights, but my shoulder is always stopping my progress..

i also dislocated it again while snowboarding and fell, but it didnt hurt and i pop'd it back myself, and the next day i woke up and i guess i dislocated it while i was rollin around while i woke up, and it just gently moved back into place?

You should seek professional help from a properly trained chiropractor, sports medicine doctor or massage therapist with the propper training. They will do a propper assessment and help to pinpoint the muscles that are weak and the ligaments that have been torn. This will help them to plan a strentghtning program that will strenghthen the muscles around the joint without risking another displacement while doing so. Please talk to your doctor before engaging in any new regimen. Good luck.

Sounds like you need surgery. This is happening way too often. Get a good orthopedic surgeon who specializes in shoulder surgery.