Social Security benefits will provide some of this money you need, but you can’t count on it to take care of everything. For this reason you need to pick investment vehicles with growth potential, like stocks and mutual funds. As you age your income will go up, but it actually becomes harder to save for retirement because of amortization. If you calculate early retirement at 25, it only takes three percent of your current income to reach your desired retirement income by 65. However, as you age you have to increase your annual savings rate greatly because you have a shorter time in which to save.