I'm an older female runner in my late fifties, of fairly normal weight, and I've been running for five years now. My issue is I've always been slow and I never seem to speed up. Brand new runners of my age join the group and are faster than me straight away. I've tried running more, running longer, doing sprints (which are laughable in their non-sprintiness), doing hills, pretty much everything I can think of but I still can't break a 12 min/mile pace. My heart rate always goes up too high (180+) almost straight away and I can't breathe if I go any faster. I've had health checks and have a bit of treated exercise-induced asthma but no heart issues, normal bp etc. I'm just depressed at always being so far at the back of the pack. Any suggestions please??