I have enjoyed cycling for pleasure and holidays for about ten years including a 12 day Pyrennean traverse and Mont Ventoux, and used to be very strong on hills. A year ago my back & hips became so stiff I had to change from a "man's style" road bike to a ladies walk through frame and during the summer my partner changed my drop handlebars for straights so I have a slightly more upright riding position. During this period my cycling speed and strength have reduced (due I suppose to my Parkinsonian problems) as well as to the new riding position which does diminish the pull between arms, legs & back. But, even if I am slower it is better to be out cycling than not go at all, and luckily my partner accepts waiting for me or doing the hills twice (ha ha).
I have also bought an electric bike, intending to use it on longer hilly excursions, but have only done 12 miles on it so far as a few days later I fell over and broke my collar bone, so no cycling for another 3 weeks!! It is great to ride but needs very careful and considered use as it is much heavier and I really have to concentrate at all times. Not as much fun as a light bike, but as needs must. . .