Do check with your doctor first if you have not done any exercise for some time, you may need to start with something easier and more suited to your needs which your doctor can advise and recommend to you. Pulmonary rehabilitation perhaps or something else more appropriate.
Here is nice short routine which I use myself from time to time. I find it does boost energy and helps keep things mobile, also helps with shortness of breath, especially if you incorporate breathing exercise into it. Slow inhale exhale etc
Unfortunately you cant always see the leg and foot movement in this video but if you have done tai chi or Qi gong before you will probably know what these are. However, just doing the arm movements alone is very relaxing and calming.
Hope you enjoy
youtube.com/watch?v=uZp_4le...
Qi Gong an exercise that helps health on many levels, physically, mentally, emotionally, helps with our mobility, balance, breathing as well.