Hello @kateia, I'm glad that you brought up the idea of chair exercises. If you don't want to buy a DVD, there are a lot of chair exercises on Youtube that you can watch for free. Here is a link to some of those
https://www.youtube.com/results?search_query=chair+exercises+for+seniors
I'm sure that everyone can find one video that will help to get moving without being harshly aerobic. They are great when you are recovering from surgery or an injury.

Here is one that looks especially gentle, https://www.youtube.com/watch?v=SaYDK_LH_uk&t=7s.

Remember you only have to do the exercises that feel good, for example, if you have leg or foot discomfort, just do the upper arm exercises, etc.