You can prepare for your retirement transition years before it occurs. In doing so, you can do your best to avoid the kind of financial surprises that tend to upset an unsuspecting new retiree.
How much monthly income will you need? Look at your monthly expenses and add them up. (Consider also the trips, adventures and pursuits you have in mind in the near term.) You may end up living on less; that may be acceptable, as your monthly expenses may decline. If your retirement income strategy was conceived a few years ago, revisit it to see if it needs adjusting. As a test, you can even try living on your projected monthly income for 2-3 months prior to retiring.