What annual return should I use?
The S&P 500 has averaged ~10%/year before inflation (~7% real). For a balanced portfolio, 6–8% is a common planning assumption. Use a lower rate to be conservative.
How powerful is compound growth?
Investing $10,000 at 8% for 30 years grows to $100,627 — a 10x return. Add $6,000 per year and it grows to $849,000. Time in the market is the most powerful factor.