Running

Contrary to what has been believed for many years, people can grow more neurons. Neurogenesis does occur, and a study by Praag et al. (1999) has shown in rats that running increases the production of neurons the most (compared to swimming, water-maze training, and an enriched environment with toys).
This increase in cell proliferation can occur as soon as 24 hours after the rats exercise. So if we extrapolate this to the human brain, one can say that if you're looking to grow some more neurons, your best bet would be through running.

I am extremely unhappy.

Extremely.

:'C