A good rule of thumb is to save at least 15% of your income for retirement. If you make $50,000 a year, that means saving $7,500 each year. If you start saving at 25 and retire at 65, with an average return of 7% per year, you could have around $1.1 million by retirement.

Compound interest is like a snowball. When you roll it down a hill, it gets bigger and bigger as it picks up more snow. In money terms, when you earn interest on your savings, your money grows and then the next time you earn interest, it's on a bigger amount. So, your money can grow faster and faster!