Keeping your energy up.

I am currently 7 weeks 6 days pregnant with my third child. My oldest is four and the youngest is 2 and yes all three were planned.  My morning sickness and exhaustion are setting in how do I keep my energy up so that I can still be active and play with my kids during the day? I don't remember being this tired with my second, although I probably was because I was getting my bachelors degree and doing an internship and working part time. We were around family then and we currently live away from family so any suggestions help!