Although this article is for people in the middle of their careers, it is a great reminder and very applicable to those thinking about and transitioning into retirement.
The article also provides a list as for ideas to broader your horizons.
The phrase is something that will remind you to get out of your comfort zone. Retirement is a time to try new things and explore the many opportunities and possibilities that await!
There is a great quote that also sums this up-Life begins at the end of your comfort zone.