Mitza, I totally understand! I am up at 3am, off to work by 5:30am, don't get home until around 5:30pm, and then time to work out. 3 kids are not an obstacle for me, it's having 2 of them being disabled, so have learned to incorporate more things I can do without going to the gym (since the nearest is another 45 min drive away). I use an elliptical in the house now, before I was able to afford that, I got a travel trailer for my bike so that my daughter (the one I couldn't leave at home) could ride in that while I pedaled
I would also put her in a wheelchair and head off for a walk, she didn't mind so bad at dusk so she didn't feel like people were looking at her (horrible stigma being in a wheelchair). I also did crunches and things during evening tv time... they were watching the tv show and mom was watching on the rug doing her crunches, lol. There are lots you can do, just have to get more creative sometimes... then you get it in before you totally wear out for the night... it is also a great wind-down from the day. Hope maybe that helps?