Why can't sex be like runing?

After doing it for the second time this year, (make no mistakes, I am talking about running!) I am tired. Pleasantly tired... so I wonder why didn't "mother nature" make sex more like running? I am going to try and convince her (mother nature!) with my reasons why sex should be like running:

• you don't need foreplay, you just put your snickers on and you are off,
• you don't need a partner who needs satisfying. If she gets tired or is unwilling you just leave her behind. (and no solo sex is not sex!)
• society accepts the fact that you do it in groups or even with persons of same sex
• it is unlikely that your partner will hurt or infect you
• if you don't use protective gear, the group of runners doesn't accidentally increase in nine months.
• you can wear white socks throughout the activity
• and...
• 

I know these reasons don't necessarily make much sense, but I don't care I am finally high (running high) again!