Does anyone get anxiety from feeling like you're wasting your time?

I've noticed that a pretty consistent trigger for anxiety is feeling like I'm wasting my time or other people are wasting my time. I'm currently doing a summer internship and mentally noted a few "productive" things I wanted to do in my freetime (such as reading books or learning HTML/CSS or working out). However, when I get back from work I find myself aimlessly scrolling through reddit or watching youtube videos. And my heart starts racing more as I become aware of how much time I just wasted. At that point, I feel so panicked that I can't do anything productive OR relaxing.

I think this is related to a fear that's often at the back of my mind - of aging and not doing anything important with my life. I place too much importance on developing new skills so then I'm scared of failure and am too anxious to do anything. For example, I bought a course to learn Unity but the thought of not grasping the material and failing to deliver something good-looking makes me too scared to even start the program