I hear a lot of people say they can't do this or that because XYZ, but it's more true that you can't because before you even tried you quit in your mind. Don't make excuses because the only person you hurt is yourself. Here is some motivation for you.
Perhaps a lot of you are familiar with tough mudder and the spartan race. A group of wounded Marines from the wounded warrior battalion, some are guys who had nothing happen to them, some were shot, some are single amputees, some even tripple, but still participate, because they have heart and they didn't quit.
"Your thoughts become your words, your words become your actions, your actions become your habbits, your habbits become your character, your character becomes your destiny." From the book Get Selected