Man often associates certain thoughts with warmth and goodness — so when those events occur, one feels heartfelt.
But for a serial murderer, the same fulfilling sensation might arise from something entirely different.
The common man may tie fulfillment to wealth, family, kindness, hygiene, dignity, or pride.
But if one begins associating with hard things — one may find solace in achieving them without pain, and the brain associates that fulfillment pattern and starts to crave it via different means.
And when one allows to choose fulfillment in unpredictable ways — through thoughts, actions, or new associations — one begins to experience life differently.