Exercise and diet aid?

While doing my exercise routine, I would like to figure out a good diet supplement to take as well. I mean, I think that exercising and a diet would be the best way to go to make sure that I loose the most in the time that I want to loose in. I think that if I see the results a little bit faster I am more likely to stick with it. You know? I have heard about Decaslim and I think I am going to check it out.