A passage that caught my eye today while flipping through Meditations:
Forget everything else. Keep hold of this alone and remember it: Each of us lives only now, this brief instant. The rest has been lived already, or is impossible to see. The span we live is small - small as the corner of the earth in which we live it. Small as even the greatest renown, passed from mouth to mouth by short-lived stick figures, ignorant alike of themselves and those long dead.
Some might find this sort of thing depressing. For me, it imparts a feeling of hopefulness. Control the instant and you control your life. It’s impossible to plan for the past, so don’t worry about it. Use what you learned in the past to make the instant better. We can’t predict the future but we can control the instant to set ourselves up for a potentially better future.