I think everyone feels this way from time to time. I know I certainly have.
The only way I can get through it is just treat it like any other job or task you have to do. Set a stopwatch if you have to, but just do however much time you think is appropriate each and every day, even if it's unpleasant.
Personally, I despise tidying up my condo, washing dishes, cleaning the toilet/shower, and all that -- I mean REALLY despise that kind of work -- but I've learned a little bit of self-control in those kinds of tasks really can change habits/ruts you get into.
Hey, it still beats punching a time clock digging ditches in some swamp.
ETA not to sounds like too much of a nay-sayer, but it might well be you NEVER get that feeling you had at the beginning, learning new stuff, developing new techniques. That's probably superstar professionals get the big bucks and all the other perks -- they just keep grinding it out, even when they don't feel like it.