It is true that basic aerobic endurance and muscle endurance are built mostly through long, frequent rides, but you want to include different kinds of training to become more versatile and not let your body get used to one kind of stimulus.
Since you can deliver a satisfactory level of endurance in a short period of time (even during the journey itself - extreme case), it is safer to focus mainly on strength. It can be riding up hills and using harder gears, but personally I'm a fan of resistance training with weights. It lets you increase the load beyond levels that can be achieved during the bike ride and allows you to work in a different planes of motion - talking about versatility. Compared with long aerobic exercise, lifting weights increases testosteron and growth hormone secretion from which you can only benefit.
It is good to add some kind of activity that allows you to stretch and reduce any movement restrictions between contacting tissues. Since I have a history with gymnastics related activities I prefer this kind of movement, but I also don't avoid yoga technics or sometimes swimming. But remember than stretching done for the art itself is worthless, You don't benefit from the ability to do a full split if on a daily basis you don't lift your leg above 45 degrees.
And finally the most important part of training - rest. This is what differs elite athletes from very good athletes. How to enhance your natural ability to heal? Everybody can tell you about healthy, undisturbed sleep, nutrient dense food, but I want to focus on less obvious methods but still accessible to anybody.
First one would be rolling which helps to loosen up tight knots between contacting tissues. You don't need expensive rollers, bottle of water (sparkling water is better because makes bottle harder) or a tennis ball is enough. It's enough to devote 2-3 minutes a session to a painful place. You can still spend more time, but only to the point when you see no further effects. And it may not be the best idea to roll directly after the workout, better let your body cool down. I prefer rolling in the evening, while watching the movie. I take a small roller ball on every trip.
Don't try this at home :)
Although I liked moving a lot since I remember, my engangement with the world of (pain) sport began right before my 16-th birthday. Since then, more or less devoted, I'm fascinated with the idea of understanding and therefore being able to control my body as well as finding and pushing its limits.
While trying different activities, I can divide the whole adventure in three phases, determined by what was my main focus during that particular period. They can be identified as: gymnastic, endurance, physique. Further info below.
It wasn't strictly sport with coaches, rules and competitions, but rather a substitute that I could find in the closest environment. When a friend showed my a couple of simple breakdance moves I immediately jumped into it. With constant changes of body alignment and a lot of spinning in different planes, it can really mess with your sense of balance and to adapt I had to develop greater awareness. And also learn how to fall safely. And often.
A bit of acrobatics was a natural addition as it requires the same set of skills: awareness, explosiveness, ability to isolate particular part of the body during the movement. Unfortunately, there is not much footage from that period and most of it in bad quality. We didn't have GoPro cameras back then and I wasn't concerned with archiving anything since I thought I would be doing this forever :)
The last two are .gif files (a way to include crappy video files in photo gallery).
In my late 20's I noticed a slow but steady drop of explosiveness and flexibility. It's not that I dropped breakdance immediately but other forms of sport started to draw my attention, activities that would allow me to develop, and do it fast. That's the trait of my character, my inner adversary I suppose. No matter how good I become I want to see progress. I need to be better than a year before. If not, I have a feeling that maybe all that time and energy wasn't spent efficient. It's definitely a flaw, short term it can push me further, but doesn't guarantee long term commitment. Endurance training helped me to shift my focus from "right here, right now" to benefiting from long term planning even at a cost of supressing actual performance. Finally I started to appreciate rest periods, but to this day I don't feel good at this particular portion of training. Endurance sports can be really humbling because nothing is granted. No matter how good you are prepared, you can ruin a 4-5 hour race in a matter of minutes. And if you fail you always learn it the hard way.
That was the time when I started to experiment with nutrition.
During my endurance period I tried to benefit the most from the given amount of time and energy. It turned out that bike was the best option, as it was less harmful than running, much easier logistically than swimming and provided the greatest joy of all three. Interested more in riding for fun than for results, I shifted towards lifting weights which I always enjoyed but did not consider time consuming enough to keep my imagination occupied. As silly as it sounds, that what I was thinking. Working out for an hour and then resting for, let's say two days? I knew waiting would drive me crazy but in such case more "active" time put into training can be less beneficial. I was ready to wait because I had the bike and didn't have to wait inactive. I don't train for pure feats of strength, I'm not trying to increase my 1 rep max since it doesn't really matter from everydays point of view. Yet I managed to put on 8 kilograms of muscle simply because I stopped eating myself during 20hour-ish weeks of training.
As a spieces, we may not know how universe operates, but we do know the equation used to determine how many bikes a person should have:
Number of bikes = n +1
where 'n' is the number of bikes you currently have.