second wind 
noun [in singular]
1A person’s ability to breathe freely during exercise, after having been out of breath: he seemed to falter halfway through the race before finding his second wind...
- After looking set to fade, Caradak got a second wind and ran on again for third, finishing a length adrift.
- Cornish had a second wind in the final 10 minutes before the break when they added two more tries.
- Suddenly, at the very point of disaster, when I have hit what mountain climbers and runners call ‘the wall,’ I get a second wind.
1.1A new strength or energy to continue something that is an effort: she gained a second wind during the campaign and turned the opinion polls around...
- At first Marx hoped that revolution in Europe would gain a second wind.
- When I got the strength and my second wind, I packed up the jeep with some of the kids' toys and clothes.
- His presence throughout the second half of the journey gave our team a much-needed second wind.