I have always had a weak lower back for about 8 months since I injured it mountain biking. I just threw it out again (yes again) a couple days and the doctors orders are no weight lifting for 2 weeks! I need some alternative exercises that will enable me to mantain upper and lower body strength. Is it as simple as push ups, pulls ups, etc? or is there something else I can do and can I do push ups and pull ups everyday?