I've only started smoking lately. Last semester I did not start smoking until a month before it was over. In that semester, I had a GPA of 2.40. I also failed a college class and dropped another. The bad thing is I'm pretty 'smart', I just had no motivation for giving any effort in raising my grades. However, ever since I started smoking daily (didn't start smoking daily until about 2 weeks before January) I currently have a 4.0 across the board. I think I try harder to produce good work so I do not fall under the typical "dumb stoner" stereotype. It's almost like reverse logic. I'm trying harder to prove it's not the plant.

Still, this probably differs from person to person. Given the right option, any recreational activity can make anyone unmotivated or lazy.