I find that "doing 100 things" works best for me when I intend to do one small thing every day.
How do I do 100 things? Assuming I want to know when I've done 100 — I have to either do the things on a regular basis, or do them irregularly. If I do them regularly, say every day, then I know after ~100 days (more or less, if I skip or do extras) I've done 100 things. If I don't, I have to track how many I've done. Doing things irregularly means I have to separately (1) do them, and (2) track them so I know, which is enough of a pain that I never actually track them and probably won't get to 100. Doing them regularly is easier in a way — it's clearer when to do things (every day!).
In other words, I make a concrete and trivial-to-execute plan for doing 100 things over about 4 months.
Is this defeating the purpose? Who cares?
What about being intentional? Paying attention? Uh. That's not in the plan. It's probably fine without that, right?