Brain injury seems to affect stamina so short aerobic exercises might be better. I would think this would be good for oxygenating the brain too. Tracking my walking over the months has given me the sense that I've improved in some areas at least and given me base level of fitness however with me my stamina depends on the sleep I've had the night before. I really want to start running again, that's my ultimate goal.

I've not read an explanation on how concussion brain injury affects fatigue, I don't think anyone knows, but they seem to think it has to do with injury deep inside the brain, areas that are still a mystery.