One word: underrated. Retirement is key to your wealth building. Yes, you can be frugal and save as much as possible. Yes, you can aim to be debt free and be intensely paying off your accounts but what are you doing for your future self. Is your future self broke while your current self is comfortable? The good news is you can start saving for retirement at anytime. The bad news is the longer you wait the harder it is going to be on your current self to build a comfortable nest egg.
Let's do the math really quick. Let's say we have a 25 year old that makes $30,000 a year. In order to have $500,000 by retirement at age 65, they would only have to put away 8.5% of their income or $212/month. Now let's take the same example and make it a 45 year old. To have the same amount save by retirement, they would have to save 41% of their income or $1,025/month. See the difference?
Let's start with the types of retirement accounts: