Hmmm...in your situation, I might campaign for a 6 month trial of 3x/week, unless I had cavitary MAC (actual open cavities or pockets of infection in the lung - shows on CT.) Also, have they talked about stopping the doxycycline while on the regimen?

My exercise regimen is morning stretching (and sometimes chair yoga), walking 4-5 times a week and playing vigorously with 2 young grandsons or my 2 yo neighbor 2-3 times a week. I also build in 2 "rest days" when all I do is stretch and maybe a short casual walk.

I also "kamikaze" clean my house - pickup, dust, mop, vacuum at full speed, with a goal of getting done in 20-30 minutes. And I maintain a large garden - mostly perennials & shrubs - that keeps me moving about 3-4 hours a week (someone else does the digging & mulching for me now.)
What is the trainer working on with you?