the trick with meditating, as Pema Chödrön teaches, is to understand that your mind is going to wander, and to put in enough time over the years practicing until the wandering doesn't bother you anymore. lol

you sort of just work on developing a gentle compassion for yourself when you screw up, rather than beating yourself up all the time.

look up her talks on shenpa, "getting unstuck." they're well worth your time!