I found lots of activities helped. My kids were the most scheduled at that age out of their peers (now we've backed off because at 8 and 9 they can self-regulate and amuse themselves much better). We did so much stuff - I literally could not tire them out. When they were at an activity (say, kinder sport, for an example) I'd be sitting watching, and that was my down time. Mind you, mine are 1.5 years apart so they could be in the same activities and I'm a SAHM, so this would definitely be trickier for you.
Another thing I started doing is waking up REALLY early (5:00 am), before everyone else. I'm an introvert and I really need that alone-recharge time. If I had slept more but spent ALL my waking hours in the company of others, it would have drained me more.
It gets better
I'm loving 8 and 9. They're independent but still need me sometimes
