Somehow you've got to motivate yourself to practice. We've talked about seeing practicing as repetition to develop muscle memory (which it is), to develop freedom (which it does), to develop confidence (which it creates). Practice to become famous, to become awesome, to be diligent, to amaze your friends and impress chicks (baby chickens). Some of the greatest performers (not musicians, or composers necessarily, but very physically skilled performers) never see practicing as practicing, they see it as playing, performing. Not investing or sacrificing, not diligence or preparation - just doing. They may be working 9 hours in a practice room, but when they emerge from that room, they feel like they were having fun the whole time. The further you can remove the repetition involved in mastering your instrument or voice from the drudgery of p.....e, the better. But motivated, visionary, diligent or not, if you don't p.....e, you won't get better.
When tuning, if you can tell you're off but not if you're flat or sharp, lower your pitch until you know you're flat and come up from there.