Exercise is all about getting the motivation to actually get up off the couch and get started. So the best thing you can possibly do is to find something you genuinely enjoy, rather than hating every second you spend in the gym.
If running just makes you want to vomit, that doesn't mean cardio isn't for you. Try biking or even a fitness class with friends who will keep you motivated. Sometimes exercising in a group with an instructor makes it a lot more fun and helps the time pass.
If you choose to use a cardio machine, don't feel down the numbers coming up on the screen. "The information on cardio machines is often wildly inaccurate," explained registered dietician Albert Matheny. Even if the number of burned calories isn't as high as you'd like, that doesn't mean you haven't had a productive workout.
Remember, if you're not feeling up to it some days, it's okay to take a break from your exercise routine. "Going hard every day over-stresses your body, leading to injury or burnout," said Matheny. So be sure to find things you enjoy with some good company, and don't be afraid to rest when you need it!