This was exactly my experience years ago. I tried and failed to make a running habit several times until I got a heart monitor. When I finally did, I figured out that the pace I thought was what I “should” be running at was actually putting my heart at 185-190 and I was just getting wiped out after a mile or so.
Anyhow I just slowed down to keep my heart more like 140-160 and at the beginning I would even run three minutes and walk one, but I managed to get up to half marathon distance.
These days I don’t go all that far but I do about 3-4 miles 3 times a week. I don’t go very fast either but I feel healthier mentally and physically when I’m consistent.
Honestly it’s not clear to me that trying to go really far or fast is even all that healthy. It can actually lead to heart damage and it’s hard on your joints. Doing something more moderate seems like the sweet spot.