Ah, Bill! Had my heart overhauled July 23 - and I was able to do some sketching while still in the hospital. Admittedly NOT while in ICU recovery! I had a triple bypass and an aneurysm repair, and never knew I had had two heart attacks. But the VA fixed me up readily, and the main surgeon came from the Cleveland Clinic.
I believe that it was about two weeks after returning home that I was able to do some work on the rifle. And about 3 1/2 weeks before I really got back into it. Not full time, for sure, but up to an hour or so morning and evening.
Just take it as it comes, keep trying little bits and soon you will be back to normal. And when you start cardio rehab, listen to the sadistic ladies (and men), and if you really start to hurt or tire, stop! I am well into my rehab now, but still have some other problems that will be fixed after New Year's. And I don't mind working up a sweat while exercising.
Best of luck to you, my friend!