As for me , I'm in the gym weightlifting on Mondays and Wednesdays ( strength training , 8-10 reps per set , chest and triceps on Monday , back and biceps on Wednesday ), I do stadiums ( 4 miles and 48 flights of stairs ) on Tuesdays , and a 15 mile bike @ about 16 MPH on Thursdays . I also play at least 18 holes of disc golf on Saturdays .
I have stayed within 1 or 2 pounds of 175# for the last 35 years at 5' 10" .

So how do you keep fit ?