Love BJ Fogg's Tiny Habits!
2025 was the first time I have been able to implement and maintain a series of routines for the entire year (still going strong), and the concept of starting tiny was a key epiphany for me. I wrote about my experiences with it recently on my blog[0], but the point you make about good first steps is a great one.
A phrase I heard some time back that has stuck with me is "don't buy something hoping to be someone." In other words, don't buy running shoes hoping to become a runner.
In my personal experience, a good first step is the smallest version of doing the thing you ultimately want to be doing. "Brush one tooth" is a great example. Doing one push-up is another. For running, maybe just getting dressed, walking outside, and doing some stretching. The idea is that it's the stuff you would have to do anyways if you were going to do a more robust/thorough version of the thing you're trying to ultimately do. Buying shoes, on the other hand, is just purchasing more stuff.