How can I increase dopamine levels in the frontal lobes of my brain, without the use of drugs?

Reduced dopamine concentrations in the prefrontal cortex are thought to contribute to attention deficit disorder and negative schizophrenia... Dopamine is a neurotransmitter that is involved in depression. Amphetamines and dopamine reuptake blockers have potent anti-depressant effects but these drugs quickly lose their benefit after they deplete dopamine levels in the brain. http://en.wikipedia.org/wiki/Dopamine#Biochemistry