My read is that he's just making the same point as the stoics (and I'm sure many others, I'm just most familiar with it from stoicism), to not expect or fall into the trap of feeling entitled to good things. In stoicism, this is the point beneath the oft-caricatured practice of contemplating that death could come at any moment. If you don't expect or feel entitled to even just living from moment to moment, then it's (in theory) easier to see that each additional moment of life is a gift, and each good thing that does happen to you, all the more so.

Personally, I struggle to actually achieve serenity and positivity from this in practice, though I do find it compelling in theory.