Ordered carrier SC500-AF, WOW, what a well built product! I've been a welder/fabricator for over 47 years using all forms of welding processes. I know quality workmanship, this has well designed construction and welding assembly.
But exercise also stimulates brain regions that are involved in memory function to release a chemical called brain-derived neurotrophic factor (BDNF). BDNF rewires memory circuits so they work better.
I started... Serotonin while not a brain chemical is released by repetitive motion. Repetitive motion such as suckling or chewing gum releases the chemical which is a blood chemical most of which resides in the gastrointestinal tract. It is no surprise that people who are in stressful situations resort to repetitive motion to deal with it.