At Walmart, I found some angled push up stands (Gold's Gym Brand I think). I do ok with push ups, well, the modified push ups anyway. I can do at least 10 modified pushups. I can do more if I really push myself, but then I can really feel it in my abs. The pushups are good for the triceps, chest and core.
Try using the workout generator (www.sparkpeople.com/resource/fitness_plan_
) and look for some upper body workouts. As someone else suggested, you could incorporate these into your walks. If you have an iphone (or something where you can put apps onto your phone), look up free workout apps. I have a couple on my iphone (Sworkit and Jefit both free ones). I haven't used them yet. Of course, I haven't had it all that that long.