I'm not going to pretend to have the same issue you have, but I think pixel has a very good point. If you smoke grass in a safe and secure environment (like in your room or at a good friend's place, with NO distractions - parents, television, unwanted guests, etc) you might find the effects easier to harness.

I have always thought that grass can act in coordination with the mind when used properly.

Then again I might be totally wrong. Maybe the best thing is for you to talk to a doctor.

Good luck.