Make progress difficult for your former self to believe.

A good test of whether you have actually grown is whether the person you were a few years ago would find the present believable. Small, steady improvement produces exactly that effect over time, even though no individual month feels remarkable.

Write down where you were three years ago in some specific respect. Then look at now. If the gap is unimpressive, that is worth knowing. If it is large, remember that it accumulated invisibly, which is how the next stretch will work too.