From The Piano Teachers Art by Isabelle Yalkovsky Byman:

My own teacher, Olga Samaroff, had two mottos which we heard over and over:                                                                                                                                                     1.  PRACTICE EXACTLY AS YOU INTEND TO PERFORM.                                              2.  EXHAUST THE PRINTED PAGE

Last summer I started golfing – kind of. My motivation was to walk the beautiful golf courses with my husband, who is an avid golfer. Before every swing of the golf club, the golfer takes a practice swing. Every time. The practice swing should be exactly as the golfer intends to “perform.” I was always far too nervous and inhibited to wind up and take that good practice swing. It was always pathetic, so that was exactly what my real swing ended up being!

The analogy is clear. If you intend to perform musically and with a mental alertness and attention to detail, practice this way – even the technical exercises.