I recently joined a gym after a quite some years. Getting fit was my my reason of joining in like for most of us. I am enjoying it, but at the same time I realised I had joined a class of studying body mechanics for free along with it ! :)
If you keep your eyes open to what all action is happening around, you will understand how the weight, balance, muscle contraction, relaxation and a lot more things that happen in our body. There are mirrors all around, so you can see how your body behaves when you do some physical activity like pulling, pushing, lifting, holding, stretching and so much more.
Even observing without the mirrors in a great way to understand how parts of your body are affected when you do some activity. This way I am gathering a lot of raw information in my brain, which some day might come out in my animation, hopefully making it more believable and interesting.
So, if you fellow Animators are thinking about having some exercise, go join some gym :)