He's 40, single, and living in one of the world's most expensive cities. How one guy plans to retire by 50 and leave the rat race behind.

• Christopher How began his early retirement journey by tracking his spending at age 30.
• Inspired by a financial blog, How aimed to retire by 50 and started a blog for accountability.
• How's strategy includes saving 60-70% of his salary and investing in low-cost exchange-traded funds.

Christopher How's early retirement journey began with simply tracking his spending.