I suppose it’s because I’m really quite good at engineering and I’m only just alright at long-distance running. It’s hard to make enough money to live on as a professional athlete unless you’re exceptionally good because there aren’t many of those jobs around. However, there are loads of engineering jobs out there that pay more than enough to live on.
Plus I think I enjoy running more as a hobby. If I had to do it all day every day I think I might get a bit bored of it but engineering jobs have lots of variety and each project is different so there’s no chance of getting bored.