To become a Millionaire in 3 years you can put at least $350,000.00 per year into a savings account if you make more than $350,000.00 per year.
But if not you'll need to be good at investing and invest money into something that will have great returns on that money.
Or create a business and work very hard at promoting and operating that business and in 3 years or sometime down the road you just may become a millionaire.
Investing in Real Estate can also make you become a millionaire if you have enough money to invest at the start.