Cycling is a good moderate exercise for me
I was talking to some local friends the other day about triathlons and cycling in general and we all came to the consensus that of all the exercises that all of us do, cycling is the easiest. I recall a mini-triathlon that I did a few years back when I was 15kg heavier than I am now and how when I got to the 30km cycling portion of the race, that actually seemed like a break compared to the other two portions which of course are swimming and running.
I do complain a lot about things but for me, cycling doesn't really feel anywhere near as intense as swimming and especially running.

When I am cycling, I rarely really feel as though I am pushing myself to the limits whereas when I go running or swimming, I always feel as though this is truly testing my cardiovascular capabilities. Much of this has to do with the fact that where I live has very little in the way of hills but also it has to do with the fact that my bicycle is pretty good quality and the gearing kind of ensures that anything I do is going to be exactly as difficult as I want it to be.

There are certain portions of the ride that I am able to get up to a lot of speed but because so many people live in the same city as me, for the most part you are going to be limited by how much mama speed you can do because it is crowded. Certain portions of it really allowed me to get to as fast as I can possibly go, but for the most part there was always someone that was in the way ahead of me and I am not trying to endanger anyone so I take it easy.

Because of this, I am never really able to get to where I feel like I need to be in order to make some sort of gains in cardio capability. Again, there are almost zero hills here, so on the flats you are limited only by the amount of wind that you are facing. none of it actually feels difficult and while everyone's heart rates are different, if I go running, I will stay above 150 almost the entire time whereas on a bicycle it is very rare that I go above 150 at all.
In a way I feel like cycling - as I have said in the past and faced some backlash for it - isn't really great exercise compared to the other two but at the same time it is probably also considerably safer than running especially.
I've said many times before that "the people who complain about running hurting their knees say this because they don't run" and in many ways I feel like this is true. however, there is no denying that riding a bicycle is going to put considerably less strain on all of your joints and probably especially your knees.
I don't think that one should avoid any exercises that strains the joints though because I too used to complain about my knees after running until I started running on a regular basis. Then, as you would expect, my body got stronger and this pain stopped happening.
For me, cycling is something I do on my sort of rest days because I know that it can be easy as pie if I want it to be and going for a 30km ride doesn't really even feel difficult.

They did a pretty good job with the city planning of the bike path and that brief moment that I got over 40km/hr was on the downside of this particular path's one and only hill. That was a lot of fun because it was at that time that I looked over to the right and realized that all of us on the bicycles were actually moving faster than the traffic of cars over there.
So for anyone that I insulted by saying that cycling is "not good exercise" just know that I apologize. My specific circumstances dictate that it is going to be less intense than running or swimming, but much of that has to do with where it is that I have chosen to live.
I do know that after I do a ride on my bicycle, that I do feel some pressure in my legs and that makes me happy to know that these are likely different muscle groups than would be activated in a pool or running on a street.
I think all exercise is good for you and while a lot of people will argue which is "best" I think the most important thing is for a person to find an exercise that they don't hate and therefore are a lot more likely to continue doing it. If you loathe the runs, there is a good chance you might need to change things up and get some variety in your workouts. I sometimes really hate the runs when I am doing them and this makes my metal game a bit tougher to keep going.
In the end I think all of us CAN do it, you just have to get the mindset that if you just don't give up, you will succeed. If you do hate running, maybe try your hand at cycling. It is significantly easier because of the technology involved and for everyone, the heart rate is going to be lower on a bicycle because of the technology.
One of these days I would really like to join a real bike race that is out of the city and the roads are marked off for us so that all the "real" bikers could teach me a lesson or two.