It really can't be said to often: Letting go is an essential theme for the last half of life. There is so much that has stuck to us as we've gone through life—ways of being and of doing things, old tapes and messages about who we are or how we act, old beliefs that don't work for us anymore, even some friendships that have really gone bad but from which we haven't known how to disengage.
At a certain age, it's time to take a look at who we really are. How do we want to define ourselves? What do we want to do and be? What simply doesn't work any longer? What would free us up to be who we were meant to be?
It's a good time to learn to say "No" if you haven't already. Say "No" to things that are unsatisfying but use up your time. Say "No" to relationships that are abusive or that aren't life-giving. Say "No" to negative beliefs about yourself—things that someone long ago said to you often enough that you adopted them for your own. (You are stupid. You are ugly. You are a failure. Etc.) Say "No" to tending to everyone else's needs and ignoring your own.
And say "Yes" to authenticity. Say "Yes" to life on your terms, to living in a way that feels healthy and right for you. Say "Yes" to believing you are worthy. You are! Say "Yes" to self-compassion and self-care; that actually puts you in a space where you're better able to show others care and compassion.
You get the idea. It all starts with "No" and with letting go.