How to get more stamina by running

You can increase your stamina by sprinting (tapping the run button) as I learned from experience yesterday. When you do the first bicycle mission you also get a tooltip that says something to the tune of "biking helps increase your stamina", after which you also go for a swim, during which I increased my skill yet again by tapping the run button while swimming.

So, in summary:

  • Tap run button while running
  • Tap run button while swimming
  • Tap run button while biking