I want to demystify the concept of 'investing in yourself' as a financial strategy, because it gets talked about vaguely.

Investing in yourself means spending money or time to increase your future earning capacity. The return on this investment can far exceed any market return.

Concrete examples:

• A professional certification that qualifies you for a $15,000 raise costs $1,500. That's a 1,000% first-year return before the compounding of the higher salary over a 30-year career.
• A graduate degree in a high-demand field costs $50,000 and increases lifetime earnings by $500,000. That's a 10x return before compounding.
• A $200 salary negotiation book or course that gets you one successful negotiation pays for itself 100x in a single conversation.

The caveat: not all self-investment produces returns. The degree that doesn't improve earning prospects, the certification in a saturated field, the course that never gets applied. Evaluate the expected return honestly before investing.

The rule of thumb: invest in skills that have direct market demand and measurable salary impact. Everything else is education, which is valuable but shouldn't be confused with financial investment.