There is something very profound in what the 20th century British philosopher says. The more interests we have, and I would add the ability to cultivate new ones, the better our chances at lifelong happiness. I have found this to be true in my own life.
I have been a distance runner since middle school, back in the early 1980's. I love to run, both the training and the racing. However, a few years ago, one of the disks in my lower back ruptured like Mount St. Helens, and I was told that I should give up running by the orthopedic surgeon who repaired my back. I still vividly remember getting into the elevator at his office and the sense of loss I felt at no longer being able to run.
In a way, this seems trivial, and it is. Given the depth of suffering that happens in the world, this is a fairly small problem. However, as I reflected on why it was difficult for me, I discovered that running wasn't just something I did, it was a part of my identity. Soon after my surgery, I went into the local bike shop and bought a road bike. Cycling took the place of running, as I was able to continue to push myself physically and mentally, and enjoy the other benefits of this type of exercise. Plus, riding a bike fast is just good fun!