Running

I did the UK variant of Couch to 5K (9 weeks, final goal is 30 minutes at any pace, not 5km) three years ago. I'd never run before in my life.

Instead of chasing pace after finishing that, I worked on increasing duration and distance. That was after realising that every time I'd forced myself to get faster I'd picked up some injury. Pace naturally increased as I got fitter.