As each new opportunity appears, you can react on a larger scale than your previous investments. That's called compounding. It's when the interest, dividends, and capital gains your money has earned begin to generate their own interest, dividends, and capital gains, and on and on in a virtuous cycle. It's how $10,000 can grow to $2,890,000 over 50 years at 12 percent.
You can keep your career moving forward by keeping your work skills sharp, and increasing your value to your employer. You should put yourself in the running for promotions where possible, and hold yourself open for better opportunities with other employers. If you are self-employed, it means steadily working to keep your business moving up to the next level.
Assuming you are doing pretty well and are happy with your current standard of living, what would you need to maintain your standard of living in retirement? Knowing you are on track to accumulate a nest egg to support that lifestyle is a big win. Gold medals go to those who have accumulated enough assets, or passive income streams, to be in a position to retire well.