Warren Buffett said
Invest in what you know.  

Buffett may have been speaking about investing money in markets that you know or understand.

The principle is the same for your career.

Bet on yourself.

What other investment do you know of that has as high a rate of return as investing in you?

Answer- None. 

You are the best investment there is.

Listen.

I am speaking to the deepest part of you,

that inner voice that knows a bet on you is better than

the wagon that you are currently hitched to.

1. You are more powerful than you believe.
2. You are more influential than you think.
3. Invest a dollar, an hour, an ounce of emotional energy in yourself.
4. You will never loose.
5. Markets are volatile.  You are steady.
6. Money is fleeting.  You are constant.
7. Risk equals reward and sometimes just a good story.