Comment by rhondapatrick

Interestingly, exercise itself actually helps get an energetically favorable type of energy to the brain in the first place: lactate.[1] Moreover, lactate in the brain triggers the release of BDNF, which causes neurogenesis.[2]

I recorded a video conversation with the pioneer of the lactate shuttle theory behind this mechanism which may interest you. https://www.youtube.com/watch?v=lThFQM503EU

[1] https://en.wikipedia.org/wiki/Lactate_shuttle_hypothesis

[2] http://www.ncbi.nlm.nih.gov/pubmed/21094220