Investing required to reach $1,000,000 by 50 with an 8% return: Age 20: $214 /month Age 25: $318 /month Age 30: $488 /month Age 35: $759 /month Age 40: $1,223 /month Age 45: $2,164 /month Age 50: $5,467 /month Lesson: Compound interest favors those who invest early. It gets exponentially difficult as you get older, so get started ASAP.