I went on a walk the other week with a friend - a walk I've done in my younger days with no problem - and half way through I was exhausted and drenched in sweat. My friend either wasn't tired or he didn't let on, but I felt like I was going to die on the up hill sections. I could've done with a good number of breaks but didn't want to come across as unfit.
My job keeps me moving all day but perhaps not as much I thought.
Anyway I really must try and get back to the stage I was 10 - 15 years ago.
Have you ever come undone by thinking you were fitter than you are?
I didn't find the right solution from the Internet.
References:https://forums.digitalspy.com/discussion/2242251/are-you-as-fit-as-you-think-you-are