Start slowly. If you haven't exercised in a while, begin with just 5 to 10 minutes a day. Build up by adding a few minutes or repetitions each week.
Add to your daily activity. Exercise doesn't only happen when you're suited up in workout gear. Add a little extra movement during the day when you can. Take the stairs instead of the elevator. Park farther away from the grocery store so you have to take more steps to get there. Take a less direct route into the house. Any extra movement counts.
Relax, actively. You don't have to choose between exercise and TV. Set up a home treadmill, exercise bike, or exercise mat in front of the TV. Choose a couple of shows that you watch only when you're moving. Or divide watching a movie into 30-minute sessions, working out during each. You'll do most of your 150 minutes of aerobic exercise in just one movie.
Multitask. It's not only TV time that can double up as active time. Call a friend or relative when you're on a walk. Save a book or favorite magazine to read while you're on an exercise bike.
If you hate exercise, think about why. Write down the five things you think are worst about exercise. Then figure out how to make them better. If you think it's boring or lonely, join a class or go on walks with a friend. If you hate the gym scene, do it at home. If exercise feels too hard, try dropping down to an easier level and build up.