I went to Machester Velodrome last night and did my first ever bit of track cycling. Fixed wheel, no brakes, 20 foot up 42 degree banking, all a bit scary and intimidating. Certainly had heart racing for the first few laps. Half an hour later it was second nature, riding in groups and taking part in training drills and races.
What have you done that seems very scary at first, but pretty natural in a short period of time?