During the summer I love exercising outside to burn fat and build muscle. Training outside in the sun and fresh just puts me in such a good mood there really is nothing like it. The other major advantage of training outside is you never have to wait for a machine or bench to do your workout! Circuit training (doing a series of exercises in a row for a set amount of time) is a great way to burn fat, but with how busy gyms are they can be difficult to accomplish. The solution, go to your local park and workout there! Don't worry, no one will see you or look at you funny, nobody uses playgrounds anymore! Kids are too lazy and parents are too busy so the local playground is your very own outdoor gym, ready to help you lose weight and get into shape!
Here is a video of me training at my local park. I live in downtown Calgary and I still always have the place to myself. This video will give you an idea of some the exercise you can do. If they are too hard, find a partner and help each other out. I always hold my fiance's legs while she does pull-ups and dips, making the exercises easier for her to do.