According to this article1, you can make yourself more clever by mixing up your daily routine with small mental and physical challenges, such as doing a sudoku puzzle, showering with your eyes closed, and eating a healthy meal (talk about a physical challenge).
They even suggests using your mouse with your other hand, which I do regularly. Thinking about it, it all started when I discovered the internet. And by internet, I mean internet porn.
1 via LifeHacker