Practice is something most folks dread. It truly is a universal feeling. Repetition, creativity, can be a strain. Personally I rarely practice scales. Only because how often does one perform scales?
Regardless, practice has to be second nature like eating.
The music will tell on you when you attempt to muscle your way through a piece. Ironically, improvisation can depend on your muscle memory. I know cats like John Myung from Dream theater who puts in almost 6 hours a pop. Drumming has a toll on your stamina if you neglect practice. So the point is – get it in, get it often and the results will make up for the torture. – DH