This isn't going to be a short answer, but I feel it's important to tell it in full.
When I was about 10 my cousin Sam got a field bike, a Honda express, from the first time I rode it I was sure I wanted to ride bikes. For several Christmas and birthdays after I asked for a bike, but never got one. Rather than put me off this made my desire to ride even greater. But I had to watch my cousin move up from the field bike to motocross, and later a moped as well, then a 125. I then brought his moped and did my cbt, and finally had a bike of my own to ride. The plan was that we would both do our full bike test at similar times an then be able to ride together, but we lost Sam in November last year, and from that point on I was 100% sure I would ride bikes for as long as I can. Because he no longer could. As kids we had planned a big trip, to ride for home, to John o groats, to lands end and home again. I dout we would have ever done it. But now I plan to do it as soon as money allows.
In short I ride in memory, because it allows me to escape and because I fucking love it.
Sorry this was so long, but I felt it had to be said.