Retirement planning needs to start early with savings. As you get closer you need to be looking at what you have saved and invested for post retirement income.
Note for 62 and older: This may sounds crazy as heck, but in may ways, Medicare is about as good or better than many previous medical plans. Not as good as those I had in previous years, but better than the chiseled down plans many companies turned to in the last few years. I do have a supplemental policy, but it is a high deductible inexpensive plan. If things turn to crap I'll be out about $5k/year. but it's $62/month. Oh, and no matter how much $$$ you've contributed to Medicare over the years, if you make too much they will charge you're more.
Before I retired I did spreadsheet after spreadsheet, mixed in all the "what if's" and price increases I could think of and took all the worst case scenarios to make my decision. I even sent my proposed budget to my financial guy who is very conservative.
In some ways being retired is less expensive than working, no work related expenses like gasoline, laundry, meals etc. OTHO, you do need a budget so you don't over spend. I'm doing more with the things I have and less acquiring, well, except for some auctions for items made of blue/black steel.
Once I quit I did not want to go back. My wife and I both worked our tails off all our lives, I didn't want a false launch. For me, the planning was like that for a trip to Mars, if you don't have it when you leave, you're not going to get it later. Even after leaving, it took some time to get used to the idea of not having to go to work again. I actually enjoy Mondays and Sunday evening.