If you've watched movies involving cross training, like in the movie Never Back Down, then I'm sure you've seen exercises involving giant tires and maybe the following exercises that I will share with you.
It's called the Sledge Hammer, simply because what you are doing is raising a sledge hammer over your head in a slight squatting position (knees are soft), and then bringing it down while engaging your core and slamming it onto a giant tire. Trust me, this sounds easier than it is.
This exercise works; I did it Saturday afternoon, and I have never had such an effective workout; I have muscles that are sore that I never felt in my life before.
I do recommend that you do not do this exercise without proper supervision, with an experienced personal trainer or someone experienced in this exercise and knows proper form to do this safely and without injury.