Congrats. Make sure you take it easy and don't push it too hard. Proper stretching helps a lot too. When I started getting back in shape a little went a long long way. Just FYI, a vertical pushup is when you do a hand stand usually with someone holding your legs or balanced against the wall. If you can do one of those, you usually can do a lot more regular pushups. Leg up crunches are like regular crunches but with your legs suspended in the air. Knee bends are just standing and squatting down about half way. I'd start with regular push ups, crunches or situps, and knee bends, perhaps a few pull ups. Work with that a few times a week along with the walking and stretching and you should start feeling better once you get past the sore muscles. I'm glad to hear you taking the time to take care of your body, it's only going to get better from here on out.
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