[MrMontyBurns]

Something along the lines of

Face the world with an open heart and good things will happen / life will pay you back.

Asking someone to play cards on the train or simply gifting someone a smile can give you a positive feeling for the day. People usually mirror how you approach them, I believe being kind will make your life so much easier because others will respond with kindness (at least in the moment).

This one encouraged me to speak to strangers as I'm rather introverted and I've been carrying the idea in my heart for quite some time now.