Husband told me that on his usual walk today, he had to stop and sit down for five minutes because he felt he wasn't getting enough oxygen.
This is someone who brisk walks a couple of miles daily, and walks 10 plus miles at weekends, so not exactly unfit.
He said it's happened once before but that was over a year ago. That's a bit odd isn't it? He couldn't describe it any better than that. Said he wasn't in pain and wouldn't describe it as being out of breath, just felt like he hadn't got the energy to keep going.