You have decided that you want to retire early and live a long and happy retirement life after age 63. The life expectancy is about 88. So, you have another 25 years after retirement to live. You think that living in $150,000 a year is "modest" enough. Assume that the return rate on investment is 6.7% for your retirement years. You're 23 years old now. You can earn about 13% return on your investment. How much do you have to put aside each month to reach your goal?