Yeah, I do nearly 22 miles each way. It's very do-able. What makes it easier for me is that I work Tues/Weds/Thurs evenings and then the whole weekend, so my week is split with Monday and Friday as rest days. That helps a lot with recovery and managing a full week. What makes it harder is that I work a physical job that itself puts a big load on my body.
The main points that work for me are the following:
Well equipped toolkit
Careful attention to eating and drinking. I drink some recovery drink after each ride, on the way in and again after getting home.
Careful attention to not taking part in commuter racing. If I do a bit of racing, I'm likely to be paying for it for a whole week, and may end up taking public transport to get enough recovery.
Lots of sleep. I'm lucky in that I get to have an afternoon nap during the week, and I make a big effort to go to bed early.
It's not that impressive, really. There are lots of people who commute considerably more than I do.