7 minute workout

So ... the only way I can do push-ups is on my knees and I need extra padding for that. I cannot do the planks, although I try. I can get my upper body up or my legs but not the whole body. Yes, I will continue to work towards doing them. Also, I definitely cannot do chair steps. I will try to find something that I can work with. I do modified jumping jacks. I am 64 years old and totally out of shape and overweight but want an exercise regime similar to the 7 minute work out. Once upon a time I was actually fit and thought about be becoming a fitness instructor. That was a hundred years ago! LOL Any suggestions? I do go to the gym for an hour six times a week. I'm not sure I'm doing the right work for myself, though.