Physical Strength? You lift weights at the gym, could kick any guys ass on the street, you own a big gun, have an iron door with a dead bolt?
Or is it Mental Strength? You're patient, lived through many tragedies yet perservered, emotionally stable, well read, never accept no for an answer?
Well, neither one is correct. No matter how much you dissect it, you will not find strength in the physical arena or the mental arena. What else is left? Spiritual some might ask? Others might say that falls under mental, it doesn't matter what gives the iron will, you have it, its mental. For the sake of argument lets leave it at that for now. So we come back to if its not physical, mental or spiritual, what is it to be strong? I would say that you're trying to answer the problem all wrong. You'll never find strength in yourself.
No matter how strong you are, theres always someone stronger, no matter how determined you are, you'll run into someone who wants it more than you do. Strength can not be guaged in such ways. Strength is found in those you surrond yourself with. Strength is knowing you can depend on others to help you when you falter. Strength is always being at piece because you know if you get into a fix that you can't get out of, your friends will be there to help. There will always be eventuallities you weren't prepared for, and you will find yourself unable to solve every situation on your own. Even if you could do it by yourself, having friends that are willing to help you through it is more powerful than any other force out there in this world to my knowledge. Whatever divine or mundane influence that compels them, surronding yourself with good friends that you can depend on and who can depend on you is where strength lies. It's not in the numbers, but the hearts and minds, and souls if you so believe, where strength resides. Never forget that, pushing people away is selfish, it's self-destructive, and it is no answer. The farther you pusher them away, the longer the journey to get them back. Even if you figure on never returning, even if you're prepared to die in the gutter, your friends won't let you, but you have to let them help you.