Just going on the reasoning that if a person or animal's stem cell production can be reduced by causing them to despair, then stem cell production must be supported by some kind of internal mechanism (like recognition of potential, or the anticipation of some kind of gain). Otherwise, creatures would die from any insult (let alone being zapped with electric current or placed in a tank of deep water w/ no way out). So here's a list of probable stem cell producing pastimes:

Food

Sex

Chocolate

Sleep (knits up the raveled sleeve of care)

Yoga

Jogging

Sky diving

Creating art

Helping others

Watching children play

Looking at the horizon

Daydreaming

Hunting & Fishing

"To drive before me the wailing wives and concubines of my enemies naked through the streets, for the review of my troops" (recommended by Gengis Khan)

Tai-Chi

Note that they all have potential in common, are voluntary & not compelled, and are fun or gratifying somehow. That Gengis should advise tormenting others as a type of enjoyment shows Psi-ops goes way back, like the Nazi SS it's existence demoralizes opposition. I'd also like to include drugs on the list, but that recommendation should be tempered a bit:

Dope makes things interesting, and allows several trains of thought to be held simultaneously (however fleetingly). That aspect (assuming something unproven is actual fact to see if it fits evidence) when carried to maturity, is indistinguishable from psychosis because ones judgments are based on a theoretical model instead of evidence supported by fact. I mean like even if aliens or the devil DOES control the Church and the Republican party, it's still psychopathic behavior, you'll freak people out, become a homeless nutcase, and live in a Van. Or else go around preaching the word of god. The net result is missing teeth & reduced stem cell production. So any recommendation of drug usage stops before it gets that far. Try the other stuff on the list first. (but maybe not Gengis's advice)

word of god