When you're depressed, you probably don't even notice smiles or resent those people! Depression has this way of painting you're world, as does happiness and, yea that mania thing.

When you're happy, you see a fairer view and you smile, people naturally smile back. If you're grouchy, you get grouch back. It's a survival thing so, if you're smiling and projecting positive energy, those around you will reflect it back at you. I try very much to fake it when I'm down for this reason.

And you're so right about Excel! Until your brain goes on a mission of sorts with the numbers. Darn "manic" missions! Doubt that is what it is for you since you're not describing any of that mad drive and hyper focus.