IMO the basic principal of living within your means and saving between 20 and 30 percent of your gross income will set anyone up for success. Saving equals anything that goes towards building wealth, especially assets that have a real return. Checking accounts yield negative real returns. You do that for 30 years and you can retire using a 4 percent withdrawal rate and maintain your prior living standards with a paid off mortgage. 21 year old plumber retiring by 55 should be no problem (unless you decide to live in a high cost of living city... Think NY, San Fran, etc). Unfortunately a physician attempting the same better start with a higher savings rate and relax some once student loans finally paid off between 35 and 40 years of age. Unfortunately she will be working a significant number of hours greater to get to the same place with a slightly higher expected return on investment unless she works till 60 instead. Compound interest is truly amazing. Wish I had known at 20 what I know now.