It's a cliché, once again, but true: Nothing is permanent except for the fact that everything changes. Everything that you think you know about yourself, your body, your job, your loved ones, your country will alter with the passage of time.
Much of the pain that we experience in our lives comes from the desire to hold on to what must inevitably change. We hurt when our parents grow old and die, and we hurt when our children grow up and move away. We hurt when we lose the strength or beauty of our youth, or the prestige that our work brings us.
If our desire for protection from pain supersedes our desire to face what is true, we are doomed to live lives that attempt to limit or ignore change. And that's sure to hurt. Lots. Of course, facing change will bring pain also. But each meditative step that we take will lessen the amount of pain that we must experience when we face and accept change andimpermanencee.
I like the point that we need to value truth more than protection from pain. In the long run, we'll actually have less pain that way. Remember, the cause of suffering is attachments - primarily the attachment to things being other than they are. And making friends with impermanence will train us to let go of attachments. Training ourselves to remember that all things change can actually be very consoling. But it does take practice.