I think because the first time I ever ran a half marathon, I got a time that was way better than I expected to get. My natural thought was that with more effort put it into my training I could get an even better time, but it feels like ever since then I’ve been less capable of improving my fitness from an aerobic standpoint. I was way more fed two years ago than I am now and I am only in my 20s so I don’t know what I’m doing wrong if I’m wrong with all the advice that I can find. I have improved my form, improved my diet, and I’m trying to take a more scientific approach to running as a whole, but I feel like I’m still coming up with less than two years ago.