I think some of the ability to differentiate a light run from a hard run requires having a degree of baseline fitness. A lot of people who are not especially fi

I think some of the ability to differentiate a light run from a hard run requires having a degree of baseline fitness. A lot of people who are not especially fit will find that they can run quickly for a minute or two, or very slowly for maybe ten minutes, but either way they find themselves completely winded and sore. Folks will read advice online about running at a pace where you can have a conversation, but find that there's literally no pace above a walk where this is possible for them. I was interested in running for years, but found the walk breaks that the Couch to 5k program uses to deal with this issue to be tedious. I tried it a few times, but it didn't stick until years later after I'd started a gym habit and built a good base. When New Years came around, I was used to going to the gym before work every morning, and it was really disruptive when my gym was suddenly insanely packed with resolutioners, so I just put my stuff in a locker and tried going outside for a run. With the base I'd built in the gym, I found I could run quickly for a few minutes, but when running slowly I could go for 30+ minutes without a break instead of ten, and it finally stuck (that was 4 years ago).