Time is the only real factor. You can work up to the miles. If you don't have home and family obligations, then a 41 mile daily RT isn't a problem.
You'll have to work up to the distance, though. You can drive partway and park the car. you can drive in with the bike, ride home, then ride in and drive home. There are all sorts of alternatives.
I get to choose the length of my commute. In foul weather I can take a direct route. Otherwise, I choose a longer one. Lately I've been doing 29.5 miles a day. It's no real problem. (For the record, I'm 56.) I just budget the time. At my typical pace, it's an hour of ride time in, then 45 minutes (by a slightly shorter route) coming home. Plus stoplight time each way.
For longer distances, the bike makes more difference than for shorter ones. I ride road bikes because their design intent is to cover longer distances quickly and comfortably. For 41 miles RT, I wouldn't advise anything else.
As for motor assisted, if you're going to turn a bicycle into a motorcycle, why bother with the scotch tape and bailing wire? Just get a motorcycle or a scooter and be done with it.
+1, all of it.
My commute is 34 miles RT and I do it on a road bike (except during winter, I have an old mtb but I only commute by bike half the time in winter)