I recently saw the movie Limitless, and I was quite intrigued by the concept. In the movie the main character takes a simple (illegal) little pill that supercharges his brain, making him able to instantly remember things he didn't even know he remembered, draw connections between things insanely quickly and other cute tricks like that. He changes himself from a confused writer into a successful businessman, politician and lots of other things. Wouldn't it be nice if such a drug existed in real life?
There is. It's called confidence. It might not be as brilliant as the drug portrayed in the movie, but the effects of it are largely the same. Personally, when I don't feel confident in a situation, I lose the ability to make connections or tell an interesting story about something that happened to me in the past. But when I'm at ease, happy and confident, I remember things from ages past that I thought I had long forgotten, and I am instantly able to relate the things I hear to other things in my area of knowledge. Oftentimes the things I am able to do when I'm confident are things that I should also reasonably be able to do when I'm not confident. The knowledge is there, the mental capability is there, but somehow when you're not confident you're not able to access it. Once you convince yourself to be confident, you'll find your own brain opening up for you.
Also, remember to get enough sleep.