I want to give a practical answer to the question I get most often from young people: 'I want to start investing but I don't have much money — is it worth it?'

The answer is yes, and here's why the amount matters less than you think in the early years.

If you invest $100/month starting at 22 vs $100/month starting at 27, the difference at 65 is approximately $90,000. That $90,000 difference came from only $6,000 in additional contributions (5 years x 12 x $100). The rest is compounding on those early years.

At 22, even $50/month matters. Not because $50/month is going to retire you, but because: (1) it establishes the habit and the account, (2) the early contributions have the most compounding time and thus the highest ultimate value, and (3) it's much easier to increase a contribution that exists than to start one from scratch later.

Start with what you have. Increase it as income grows. The amount matters less than the start date.