Student Loans - Pay them off or keep them?

I hate to follow a post about the virtues of debt with a similar post, but this occurred to me today, as I paid $150 toward my student loan debt, even though no payments are due for another 8 months.

Why am I paying ahead of time? It is human nature to not want to owe anything to anyone, especially money. I had this instinctual urge to see my debt number go down, so I went ahead and pressed the "Send Payment" button.

At a time when the stock market is making 8-12% gains a year, and the number of low-cost index funds that exist, maybe I could have made better use of that money? After all, at that rate invested in a stock market index fund, my $150 might be worth $160 in 8 months.

And then I realized it.

I can rationalize percentages all day long, but when it came down to it, such a small dollar amount of return just wasn't worth the instinctual guilt I felt, every time I looked over at my debt numbers.

And so, I have a new rule. Any time I'm not using cash to pay debt or save, I need to get at least $100 back, regardless of the return rate, or else it just isn't worth the guilt.