Random happiness hack

Stumbled across this by accident a few weeks ago, was walking through the park and stopped to give a hand when I saw someone clearing broken glass up. The gratitude of dog walkers was a real eye opener, and I left with quite a positive vibe/spring in my step. So I experimented with it a couple of days later, same again.

Now I go down there, stroll around listening to the birds and clearing what I may find once a week. I get a nice bit of chill time away from everything, the gratitude is relentless and my productivity greatly increased.

Was wondering if anyone else had weird tricks like this?

To be clear is this not remotely altruistic, entirely for my gain.