A habit can be tied to another behavior. Using the idea of habit stacking,

The individual impact of any one piece of gratitude is small, but the cumulative effect is huge.

You start to realize how insignificant monetary things are for your day-to-day happiness. The majority of your grateful moments don’t cost a dime: time spent with friends and family, something nice someone said, a good workout that day. 

The gratitude habit is incredibly small. There are not many habits that you are able to pick up immediately and follow every day.