Similar to Yoga, going to the gym is one of the best things a full time parent can do. It will provide you with all of the benefits that a session of yoga would provide you, but the difference it the socialising aspect. When you are doing yoga at home for example, the only person you will be socialising with is you kid if he is young enough, and that just means you will be getting zero conversation!
But if you go to the gym, there are so many classes that you can sign up to that you will meet loads of people! The chances are the people that you meet in the end will be in the same position as you! They will be looking for a way to alleviate stress and many of them will be parents or single parents who want to get out of the house and feel like normal people for a few hours!
Going to the gym is great for you physically, mentally, and emotionally for the same reasons that doing yoga regularly is. The main difference that sets it apart from yoga however, is that you will also be able to socialise and meet new people. That is the one thing that you feel you lack if anything being a parent. The opportunity to meet new people and to socialise outside of your home. With the gym, you will be able to do so and meet people who are specifically in the same situation as you who can empathise with you about the same things!
As a parent or not, it is always great to meet new people and make new friends. It will lead to internal growth that you may not otherwise consider, and it will allow you to really consider being an independent adult again.