I received an injury to my left shoulder 4 yrs ago and have steadily since made my left shoulder a formidable foe. I still howver, have been loking for stretches and excersise to further my lefts and rights strength without weights. any ideas? I already have for stretches, R.A( Right fully extended) across chest and left fist 'bracing r.f (Right fist)..and vice versa, and push ups aso help ant others?