second wind

second wind
    n 1: renewed energy or strength to continue an undertaking; "She
         had dinner and got a second wind to finish painting"; "the
         employers, initially taken by surprise at the pace of
         developments, regained their second wind"
    2: the return of relatively easy breathing after initial
       exhaustion during continuous exertion
    

24 Moby Thesaurus words for "second wind":
      new birth, palingenesis, palingenesy, reanimation, rebirth,
      recrudescence, refreshment, regeneracy, regenerateness,
      regeneration, regenesis, rejuvenation, rejuvenescence, renaissance,
      renascence, renewal, resurgence, resurrection, resuscitation,
      revival, revivescence, revivescency, revivification,
      second youth