Don't mean to disagree with your pro, but CONFIDENCE can do wonders for your game. If you get two good wins under your belt with a nice margin (6-0, 6-2 etc.) that means you may be able to go for a bit more in your match. Don't go all out, but it means you can go for a bit more.
Confidence is a great thing and in the very very early stages of ones tennis game winning feels good no matter how it's acheived. For me, though, a 3.5 wannabee, nothing feels as good as a win knowing I played my best tennis, now that's a confidence booster.