What is a Midlife Crisis?

As I approach 40, I've come to realize that my biggest mistakes were not the choices that I've made or, surprisingly, even anything that I did - rather, my biggest mistakes and regrets are what I did not do. It seems to me that most mid-life crises arise from foax finally realizing what they want to do, but it being too late - or them believing it's too late - for them to do it. Luckily, with a few exceptions, it's not too late for me to realize the things that i've always wanted to do - I just need to go about doing them (for example, getting over my fear of heights). Hopefully you'll hear more about this in the future!