The first rule of self defense is knowing what you're dealing with and exactly how far you're prepared to go the second you make a decision to confront. If someone is following you and you decide to initiate violence, you'd better be damn sure you're ready to kill that person because they may escalate to that level very quickly, especially in a concealed carry state.
Trayvon Martin made a choice. He likely saw Zimmerman as an easy mark and decided to bow up. He was dead wrong.
Why? Because you watch CSI? Dude, STFU.
Actually, a 35 year old man is exactly who is going to be afraid of a fight. Because 99.9% of 35 year old men haven't been in a fight in decades and quite frankly have a well founded fear of today's teens. There are stories all over the news about teenagers walking up and just punching people in the face for no reason, knocking them unconscious. in St Louis, a teenager KILLED a man over the summer doing exactly that. Another guy hasn't been able to work or even go outside because of the concussion level he suffered at the hands of a THIRTEEN year old.
People have the right to defend themselves. Any person who decides to escalate a situation to violence had better be prepared for that situation to escalate further, especially when they're dealing with someone who has something to lose.