Help Diplomat become a better Squash player

[Diplomat]

So I've been hovering around the 3.0 range for some time and don't really know what to do. I've been taking lessons but I really think it might be my fitness/coordination/etc. that's the problem (I'd even say my technique and overall skillset is above my actual rated level).

Anyone ever done any serious training for squash? Right now I play 2-4 times a week, my diet is ok (probably too many sweets, too much booze, the usual vices) and I lead a pretty inactive lifestyle outside of squash. I'm also 27 yo if that matters at all.

Any suggestions for training, etc. would be great.

-Diplomat