Your cardiopulminary system is significantly above the mammalian norm, allowing you to exercise for longer than usual. This comes in two levels:
Level 1: You loose FP from physical exertion at half the normal rate. This does not affect mental or supernatural FP loss. 3 points
Level 2: As above, but you recover FP at double the normal rate. This is appropriate for most flying birds. 10 points.
Increased endurance can be taken with Fit, Very Fit, Unfit, or Very Unfit; the effects stack. A very fit goose (with Increased Endurance 2 as part of its racial template) would lose fatigue at one quarter the usual rate and recover fatigue at four times the usual rate.