Here's a 20 minute work-out you can do just about anywhere. Everyone can find 20 minutes a day for themselves -- no excuses! You'll be happy you did the work now --- especially when you get older. On a recent trip back east, my mother even said, "I wish I would have started doing all these good things 10 years ago." Those were difficult words to hear, but I'm happy she finally "gets it".
If you are unable to perform some of the exercises, do the ones you are able to do, and build your reps and sets accordingly. As with any exercise program, you'll get out of it what effort you put into it, so don't make it too easy for yourself, but use your best judgment. It's wise to consult your physician before starting and exercise plan.
Add a 30 minute daily walk and notice a big change in the way you look and feel!