When I re-started riding a couple years ago, I needed to re-learn some pretty basic things, like terrain that looks flat can actually be sloped, and how much difference that makes. I did not have a heart-rate monitor, but gradually re-learned that using the gears to keep my cadence up (i.e. shifting down instead of pushing harder) helped keep the worst of my gasping for breath under some control...
I finally got serious about it when I started keeping a training log - writing it down just made me want to go out more often. Also motivating was the idea that I might not have the luxury of another summer to actually get in decent shape again, what with the pandemic and all.
In the longer run, I believe that keeping it fun is key.
So, have fun!
