Wasa,
There are alternatives to using a gun for self defense especially in an activity like running and biking. The weight of even the smallest caliber hand gun can make it uncomfortable when engaging in aerobic activities. You might want to look into a small stun gun. They can be concealed in your fanny pack and are quite effective in holding off a possible attacker. From what I know about you I don't think you are the type of person that could take another life but popping a cap in their head. Unfortunately if someone is crazy enough to attack another person in a violent manner they are crazy enough to take the gun out of
you hand and use it on you. Unless you want to go through all the proper gun training and resolve yourself to the idea that you could
indeed end someone else's life by using it you might want to consider an alternative.
When I spent a short time of my life as a cop the thought that I could use a gun to blow someone away with out a second thought scared me.
I still have my gun but I don't think I have even looked at it in several years. The thought of protecting yourself by taking someone's life is somewhat acceptable in theory. But if you are ever confronted with exercising that theory in a real life situation it is quite traumatizing and could end up emotionally devastating.
Your crazy enough as it is, check out a stun gun and I'll let you test it out on me.
Dave