A thank you does go a long way; furthermore, a little respect for her time will go farther. Giving her a thirty minute break here and there will lead to a better environment all around. She gave up her career dreams, independence, and time to care for you and your children. Let her at least pursue a hobby or find a little okay room with time outside of mom/wifey duty. 30 minutes a day is enough time to train for a 5k or have a small garden or visit with the neighbor.