You were younger. Every door you opened was a seemingly infinite road in to a wondrous future. Everything existed only in the realm of possibility and promise for you back then.<p>Now more of your life has passed and a larger proportion of who and what you are is already behind you, fixed and unchangeable. So now your view of the future is that it short, too short, and only getting shorter. Now every door that opens is a potential waste of time and energy, which are now finite and precious resources.<p>The cost-benefit equation changes over the span of your life. The relative value of things changes. Back then, you would spend any amount of time, just to pass the time on something, anything vaguely interesting really. But now, you would spend any resource just to have more time in which to idly do things. But how can you just idly do things? Soon you will be dust, and the things you have done are who you will have been. You can ignore that as an immortal teenager, but as each decade passes, the spectre of your own mortality looms larger.<p>Anyway, you probably wanted more concrete answers. But for me, I try to just tap in to that cosy nostalgic feeling where I don't feel like I have to achieve anything, and just find something I can lose myself in to, with no purpose but to pass the time as if time were an infinite resource, there to be wasted. I think, perhaps, you may be getting a glimmer of that feeling from the audiobook, but your sadness about how far away that time is, is taking you out of the moment? Or maybe you just have something else going on in your life, like a soul-crushing job or something like that, and that needs to be dealt with first... Some time and space for reflection might be called for.