Which makes you feel worse?

Having a gain on your portfolio that is worse than the gain on the index.

OR

Having a loss on your portfolio that is worse than the loss on the index.

Which makes you feel better?

Having a gain on your portfolio that is better than the gain on the index.

OR

Having a loss on your portfolio that is better than the loss on the index.

How does the joy of making 10% feel compared to the pain of losing 10%?

Asking questions like this and answering them with extreme honesty will help you identify some key elements of your portfolio management style, how you handle risk and how performance affects your desire to modify your portfolio.