9 things to do in your 20s to retire by 40

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It's possible to retire by 40 ... but you have to start preparing today.

Retiring by 40 is more than possible. Plenty of regular people have done it.

Take "Mr. Money Mustache," who averaged a $67,000 annual salary working as an engineer for 10 years before announcing his retirement at age 30. Or Jeremy Jacobson and Winnie Tseng, whose combined annual salary of $135,000 was enough to retire in their 30s with a multi-million dollar net worth.

If you want to do the same, consider these tips and strategies from regular people who retired before age 40.