I just start with the shortest Sufferfest videos, and in Level mode. Turn off the power display and just ride by feel. Then throw in some of your favorites.
I’ve been down for over a month first with pneumonia, and now residual bronchitis.
A few days ago I could only manage 9 minutes of Earth Cycle. Today I rode Igniter. Over the next week, I’m planning on Recharger, No Place Like Home, TGTTOS or TWO.
Basically you’ve got to make it enjoyable first. Retest in a few weeks to establish a baseline for training.