Maybe instead of "happy" you could note moments when you feel "flow," a kind of energized, full, concentration on something challenging that you are doing?

I feel that most of my truly "happy" moments happen during or after periods of "flow," and flow is easier to identify for me.....

If you look up "flow" online you see a lot of descriptions on it.

A person cannot ruminate when in "flow." And "flow" is inherently positive and forward looking. When I am depressed it is hard to think about being "happy" but I work towards finding activities that produce a feeling of "flow" and that can help...