What's a good self-defense cl I can get in that will give me a good workout and teach me how to fight well?

I've been going to the gym off and on lately, I'm starting to lose interest in it. I use to go religiously everyday and I really enjoyed it but now it's dull and boring. I figured I want to do something more interesting such as take a kickboxing cl or any other self-defense cl. I'm wondering now what is the best self-defense program I can take that will give me a good work out, get me bigger, while gaining more stamina and learning how to fight? Do most self-defense cles come with a gym as well? My plan is to quit my gym and get my complete workout from a martial arts cl, is this possible and what is the best martial arts program to go with?