I did not start cycling until five years ago, at the age of 56. Now, cycling is my main outdoor activity, eclipsing day hiking, backpacking, and kayaking. I have found that cycling is less stressful on my aging knees than and allows me to see and experience more of the great outdoors than day hiking or backpacking. At my best I might hike twelve miles a day, but I can easily ride two to three times that distance in far less time. While I will often hike, backpack, kayak and cycle alone, I rarely enjoy paddling, hiking, or backpacking with more than one or two others, but at least monthly cycle with groups from half a dozen to two dozen. The social aspect of cycling with these groups has become as much a draw as the physical exercise and exposure to the outdoors.
I don't do much riding with others. I have some health issues that make it challenging to keep commitments.
I am 62 and I used to be an avid runner. Long story short, due to continuing and significant foot & leg injuries, I have given up running. But - there's great news: I still enjoy hiking (with mid-height lightweight breathable boots) and my true passion is a return to bicycling.
Not always, but I pretty much road bike when it's hot and ride off-pavement when it's cool or cold. I loathe riding on most public roads but fortunately I live close to about 96 miles of multi-use paved trails (Silver Comet Trail & Chief Ladiga Trail).
When it's too wet to ride mountain bike trails, I ride fire roads, gravel roads, and I have discovered other places that are great to ride (without damaging the singletrack trails but still getting in the woods and having a great workout).
When the temperature is hot I ride slower, I stop and take breaks, and I embark hydrated and remain hydrated while riding. Riding in hot conditions, my mindset is simple: enjoy being outside and I have no desire to reach any number of miles or achieve a specific speed. When it's hot, I'm just looking at "time on the bike" and, most important, insuring a safe return without any damage to my body. It can be done if you're very careful.
I am particularly cautious about dehydration & heat stroke because ~eight years ago I ended up in the hospital after a jam-packed weekend of hiking, mountain biking, and aggressive off-road motorcycling. I never thought I would ever experience dehydration and heat-stroke but let me tell ya, it was not fun. Now, I pay much more attention to what my body is telling me.
I have two road bikes - one is a traditional road bike - it's light and fast. The other bike is a "hybrid" bike - it's heavy, slow, and it was purchased used for ~$500. Both bikes are a good fit for my body size. The heavy and slow hybrid bike is now comfortable after I added new pedals, Ergon grips, and a good saddle - it's absolutely perfect for quick workouts and short trips (20 to 30 miles). For extended rides I drag out the traditional road bike. I love both of those bikes.
For mountain biking I use a hard tail, a full suspension bike, and I also ride an ancient 3x9 26er - I just can't bring myself to get rid of that old relic (ha).
I find it interesting: in my experience, the more time I spend riding a bike, the stronger my fondness and appreciation grows for that machine.
Sorry to ramble - too much coffee this morning? (ha)
Ride safe, ride often - enjoy!