I didn't have much going on for hobbies either - I worked all the time, then became a mom 3 years ago, and am still working full-time. Not much time for hobbies and not much energy either! Then I saw a bead store had opened up near us and they held jewelry making classes. I tried it out and I've been hooked ever since. I've made a bunch of pieces for myself as well as for friends and family as gifts, and have also managed to sell some of what I've made, including special requests that some people wanted. I have really enjoyed it because it is a good creative outlet. A few of my friends have gotten into beading as well, some others are into knitting, and some do scrapbooking.
My mom was never one for any hobbies - even after we were grown and gone and she retired, she still just preferred to go shopping, or play cards or go out to eat with friends. On the other hand, my aunt got into painting after she retired. At some point you might find you have more time on your hands and will need something to keep you occupied. It's kinda funny in a weird way, but when my mom passed away this past summer, my brother and I had to come up with an obituary, and what the priest could say about her. They asked if she belonged to any clubs - nope. Did she do volunteer work - nope. Did she have any hobbies - umm, not really, unless you count shopping (and boy could she shop!). God bless her, it might have been nice to see her get involved in something, but then again, she was happy the way she was, she already felt fulfilled, she didn't need anything else (of course, we think she may have had a shopping addiction and some compulsive behavior issues in that regard, but that is another story!).
If you are interested in photography or yoga, that's a fine place to start. Just tell hubby that you are trying to get into a hobby and that's what you are interested in. And if he is willing to pitch in and watch the kids more (not that he isn't already), it will give you more time to pursue it.