For reliable, steady weight loss, it's recommended to work out for at least 60 minutes a day, 5 days a week. If that sounds too daunting, then get into high-intensity interval training and do mini workouts that get your heart pounding like crazy. Strength training is ideal for long-term weight loss and maintenance, but if you want to speed things along, cardio is especially effective. The best activities for slimming your sides are running, cycling, dancing, swimming and even regular walking.