I know someone who Lost All their weight without exercising for a year. Got flabby - that is why its important to combine nutrition (healthy even) with good amount of exercise; kickboxing, powerwalking, running or try bicycling.
This is a Quick HIIT Treadmill Workout I use when I've not got time to put in a long run or the weather outside is awful. I love this workout as it get the heart pumping and I get a post workout buzz once it's finished! http://www.busyfitmama.com/quick-hiit-20-minute-treadmill-workout/