While a keeper doesn't need to be the Incredible Hulk, he does need to be able to lift his body weight. Anytime you workout, it's important that you warm up. Warming up means, a short jog, followed by a complete stretch. By the same token, following your workout, it's important to warm down and stretch. Finally, one important thing about an off-season training program, take some time to do nothing.
Rest is important.
Burnout is a real problem in sport. Too many times I see keepers go straight from their outdoor season, right in to an indoor season and all the rigors of training full time for both. Your body and mind need a break. Some things need to be done just to have fun. When you're doing a fun workout, keep it fun, but know that it's different than a hard workout.