If you haven't really worked out since your gym class days, then a St. Patrick's Day marathon is probably not in the cards for you. But a 5k by then is likely doable, and having a race or event in mind can help keep you motivated.

If you're not into racing, then set another goal that works with your fitness level. Maybe you want to move up to the advanced yoga class by spring or even just make the most of your newly acquired gym membership. Whatever it is, make your goal something that gets you excited to work out, but isn't so ambitious that you're setting yourself up for failure. "Remember to push yourself, but not to the point of feeling ill or injury," says Angeles Burke, Celsius.com Fitness Ambassador. "In order to see the changes you want, you must challenge yourself in a way you never have before."

Lack of time is a common excuse for skipping your workout, so you've got to make exercise a priority in your schedule, says Janette Janero, a personal trainer and group fitness director at Florida International University and The University of Miami Wellness Center. "I recommend setting aside one hour for walking and 15-second stretch holds for each major muscle group at the end of the workout," she says. "Setting aside this time every day will help you get used to incorporating exercise into your schedule, even if it is not at a high intensity just yet. Routine helps condition muscles to be prepared to handle cardio activity."