As others have said, give it time, and keep working. Also watch out for hammering big miles on a starvation diet. Exercise to maintain muscle, but don't slam yourself every direction.
As others have mentioned, a few rest days may help.
I do a lot of bike commuting, so once I start on a ride, I don't give myself any choice but get to the end, whether it is 5 or 10 miles away, or 20 miles, or 150 miles.
As one does longer rides, the short rides will just seem short.