Birthdays get less significant as you get older (idea)

Do what I do. Only celebrate birthdays when they're at a power of two. They're all milestones, anyway:

• 2: Useful self-awareness.
• 4: Fully mobile and ready for action.
• 8: Old enough for unsupervised activity.
• 16: Even more unsupervised activity, and with Dad's car, yet.
• 32: A good time for the midlife crisis. Have you made your billion¹ yet?
• 64: Retirement, a year early. Shame about the billion, but you're got your IRA/RRSP right?
• 128: Let's face it, you'll never see it.

Note the beneficial effect of spacing them out further and further. Thus it dovetails nicely with DMan's idea.