Of course it's his choice. No question there.
My thoughts though depict my nature. It is in my nature to work as hard and as long as i can to create as much good as possible. The skills and talents i have create, and it is my responsibility to create as much as i can. A musician needs to create music. A builder needs to build. A painter needs to paint. Yes i will retire. But not until i am done and have a feeling that i have done my best.
Maybe Collison is there? May he be happy in all he does.