Over the last few years, I've often wondered about the right heuristic for deciding which hobbies to pursue.

"Enjoyment" or "passion" get thrown around, but I've found it's not that simple. Some hobbies create a lot of joy/pleasure upfront, but that enjoyment doesn't necessarily increase with time (e.g. fine dining [1]). Others aren't necessarily fun when you start learning them, but you can get better for years and years, and the enjoyment keeps increasing, too (e.g. tennis).

Besides, there are only 24 hours in a day.

Two years ago, I came up with a somewhat unusual metric, but I've found myself coming back to it ever since. 

The heuristic is pretty simple: "When doing thing __X___, how easily, and how long for, do I forget that I have a smartphone in my pocket/backpack/car?"

(Winner so far: fly fishing.)

[1] I realize many foodies will disagree. I believe they enjoy each meal more as their knowledge increases and palate gets more educated. It just doesn't work that way for me.