Its only a fitness thing to a point. Some people are just hill climbing people, others are distance people. I am married to a hill climber who takes great delight in spotting a lycra clad road on a carbon bike going uphill and setting off on the chase. He can catch them, overtake at speed and maintain that all the way to the top on any bike including a fully laden touring bike! He looks at me with the pleading eyes that say "can I" before he sets off, I just consent and tell him to wait for me after the top (hate stopping at the very summit - need to get passed it to recover, then stop). He just likes putting them to shame
Me, I am a plodder uphill. When I run out of gears, I just plod and will eventually get their without having to stop (assuming I haven't been in hospital the day before
). On tour, I average 8-9mph (if that) but I don't care. I am not after speed, I am not after distance, I am after just getting there! My commuting is also the same - just faster, always with panniers and I think leisure riding has become the same simply because I spent so long touring, not to mention the various medical issues which mean just getting up some days is difficult! (In fact I am about to give in on that front and try for some sleep and leave my OH to our guest when he arrives!)