"Another one bites the dust..." - Queen

I'm writing this from my porch. It's nice to be able to work on my porch and take advantage of the WiFi, the shade, and the scenery.

Today I went to Urban Active. Originally, I wanted to do a really tough workout, but I wimped out. So, instead I just did some upper body stuff. Later, I may go for a short run around the block. I don't know.

Here's today's adventure:

• bench press
• no weight, 15 reps
• 10 lbs on bar, 3 sets of 15
  
• incline bench
• no weight, 3 sets of 15
  
• decline bench
• no weight, 3 sets of 15
  
• pulldowns
• 55 lbs, 15 reps
• 70 lbs, 15 reps
• 85 lbs, 10 reps
  
• flys
• 10 lbs, 15 reps
• 15 lbs, 15 reps
• 17.5 lbs, 15 reps
  
• curl bar
• 20 lbs, 15 reps
• 30 lbs, 10 reps - I got bored
  
• barbell curls
• 17.5 lbs, 2 sets of something I forget
  
• behind head tricep exercise
• 17.5 lbs, 15 reps
• 25 lbs, 2 sets of something
  
• some ab stuff

Overall, it was an ok workout - didn't push myself; this felt more like light exercise. I think I'd push myself more if I were working out with someone or if I were going for a goal, but I am goal-less.

One thing I do wish to know is why I have such trouble with the decline press. What muscles does it hit differently than the other versions of bench press?