Its not all in one go, it's something you do, say, you go to the gym. 5 reps of something easy. Hit the bike for 5 minutes. More reps. Treadmill, reps, yoga, reps, bike, reps, treadmill, reps, yoga. If you cant do 50 (arbitrary number) then you have a goal, do the same thing each time you go in. You'll hit it before long. If you find that it's not really hard. Fantastic, you've got a baseline. Next month, maybe add 5 pounds to your routine.