Learning a new and at the time somewhat obscure (in my setting) foreign language when I was around 30 taught me this lesson at the time. I did well in the small class I attended with others, but not as well as some of the far younger students with both more free time and perhaps better age-given baseline performance at language acquisition (though this is not entirely clear-cut scientifically).

I realized it didn't matter. What mattered is that I progressed toward my goal at whatever pace I could muster, not making it a race. Interestingly, this mindset has made me willing to take on much larger and more complicated challenges in general, one day at a time, without feeling overwhelmed by the mountain to climb ahead.