Tendonitis doesn't come from weak tendons. If your tendons are weak they will snap not get inflamed. It's tough it's a result of everything you did in your past plus age, it takes along time to recover from, and won't help if you do nothing. Set routines and programs are not good for it because it requires a lot of feedback. The absolute best thing you can do is dedicate some time to them. For example 30 minutes one day warm up rub work the joint ice compress then warm up again. Then you have to completely rest it the next day. If you did all that for all your joints I would expect you have a million dollar contract with the NFL.
For a working man, you have to try to make sure your diet, and technique in everything you do is perfect. Try to make sure your daily activities are done with minimal damage. Your routine should be pushed but only after you have conditioned for it. Try to swim or do some form of cardio to have good blood flow, and make sure you have at least one day of rest I would try for two.