You might like this cartoon I drew a while back :).
I feel like I often forget that the reason something feels hard is because there is a reason it's hard. In particular, that I often feel particularly out of shape when running up hills and get frustrated with myself, forgetting that perhaps it feels harder because running up hills is harder. Your comment about feeling tired but not realizing it might be because of your run the day before reminded me of this.
Thanks, Zan, I needed that cartoon :)
We have a tendency to do things that we find challenging, because that makes them interesting and new and difficult and gives you that great feeling of success when you achieve. But, important to remember that these things ARE hard!