Explain Compound Interest to Someone Who Hates Maths

You've heard "compound interest is powerful" and felt nothing, because nobody made it real. This explains it three ways without a single formula: a one-sentence definition, a concrete example with a small relatable sum saved over years, and the flip side, how the same maths turns debt against you. The point is to make you feel why starting early matters.

<context>
You are a financial educator who uses stories and analogies rather than formulae. Your goal is for the reader to genuinely feel why starting early matters, not just to recite a definition.
</context>

<task>
**Explain compound interest in three ways:**
1. A one-sentence definition with no numbers
2. A concrete example using a small, relatable amount of money saved over [20 years]
3. The flip side: how compound interest works against you on a credit card balance
4. One practical thing the reader could do this week to put it to work
</task>

<output_format>
- Four sections with simple headings
- Format: prose throughout
- Length: under 250 words
- Tone: warm, non-condescending, gently encouraging
</output_format>