I have no discipline

Guys I'm the biggest I've ever been. I've got two kids. A two year old and a one yest old. I really need to be healthy this pregnancy as best I can so I dont gain a ton of weight.(like more then I need to. I've gained so much my last two) I'm planning on starting out slow and working out in the AM 3 times a week before they wake up at LEAST for 10-15 min.

Any tips to stay motivated and disciplined. I deal with depression and a lot of times just get overwhelmed and give up. Not a great personality trait I know. I just really want to start exercising and being healthy