concentration

[tommo]

some days I can concentrate like none other.

In my advanced math classes and theoretical physics I understand everything and can point out the mistakes the professor makes. I feel this way once or twice a week and it is incredible.

But then on other days once or twice a week, like today and yesterday, my mind wanders constantly. I even notice it happening but can do nothing about it.

Most days lay somewhere between these two extremes

I am much happier when I can focus on things.

Does anybody know any methods or supplements I can take to cultivate this concentration?