This always is made to sound easy but I can count on one hand the number of "habits" I successfully built around things I didn't want to do. Getting up in the morning to go to work vs skipping morning classes back in college is the main one. But it's still unpleasant and I still just do it because that's how I get paid, not because it's a "default." "Not eating as much junk food" was a slightly easier one - because you don't buy it once when doing groceries and then it's not available during the week - but exercise or other un-fun decisions you have to make every day? Nope.