I noticed that lately I've been watching my portfolio a little more than usual. If you own stocks, then I bet you have too. Personally I'm looking at more than a 20% gain in my core portfolio in the last few months. When the bulls are running it's hard not to pay attention. Watching that bottom line grow fatter and fatter is a lot of fun.

I've also been sitting on a ton of cash, and regretting that I hadn't invested all of it back in January. There's a little voice inside my head that's telling me to dump it into the market now in order to take advantage of the gains yet to come. Every day the market finishes up the voice grows a bit louder and my feeling of regret grows.

What's keeping me from pulling the trigger? Trees.

I look out the back window of my house and see the trees just beyond the fence. They remind me of the old saying, "Trees don't grow to the sky." In fact, they don't even grow all that quickly for more than a few weeks in a row.

It's been a terrific spring here, plenty of rain and perfect growing temperatures. The trees have greened up and thickened incredibly over the last few months. Where all this growth energy came from I'm not sure. I think it's energy pent up from a long cold winter and the excellent growing conditions. One thing I am sure of is that it can't continue. Sooner or later these trees will have to slow down and take a breather. Summer will be hot and dry. The sprint through spring will catch up to them, and they'll need to pause for a rest.