I am in my mid-50's and now that my kids are grown and gone, I am preparing more aggressively for retirement. The first thing I figured out was to determine what I can control and what I can't.
I can't completely control my rate of investment return or my health in retirement. So, I work on what I can control.
I can control my rate of savings (I continue to try to increase it). I can control at least some of my expenses, particularly as they relate to debt. I have paid off all of my non-mortgage debt and am now working on that (I don't see how you can retire and still have a mortgage). Our house, while big, is smaller than our old house and cost at least 30-40% less. A smaller house in addition to having a smaller mortgage usually has lower real estate taxes, lower utilities, and since it is smaller, it won't hold as much "stuff" (things you think you need, buy and then never use).
Overall, I can control my expenses by determining what I need, want, and can do without. I pay for what I need, decide when and what to pay for the things I want, and make every effort to stop paying for the things I can do without.
I can diversify my investments not only for a diversified portfolio to decrease risk and volatility (hopefully), but also tax diversify to try to reduce my income taxes in retirement.
I can protect my assets with appropriate life, health, disability, long term care, and liability insurance.
I can spend a little money now to travel and enjoy the good health I have now, but have no guarantee to have in retirement.
You could argue I am taking a 'glass half empty' approach and I am. I would rather be pleasantly surprised in retirement than terribly disappointed.