Seriously. I'm reading his biography and everything he does is badass. He's lead a life most men couldn't even dream of. I hope my life adds up to half the adventures he's had.
I mean, here is a guy who historians consider one of history's greatest presidents, and he declined to have a third term. They were going to let him break the rules he was so good. He did safaris in Africa and started the national park conservatism in the US. When he was head of the Navy and a war broke out, he resigned to lead his own troops in battle. Let me say this again. He had input in how the war overall was run, but refused to sit in the back. So he resigned to go lead his own elite unit of "Rough Riders" on the front lines.
Badass. This is the guy who originally lived "Speak softly, and carry a big stick." But the most badass fact is summed up in the advertisement below from the Smithsonian.
UPDATE: Someone much wiser than me corrected the above statement. It's an art student project on advertising. Still gets an awesome point across though.

Source
This is how I want to live my life. Best description of Roosevelt "Death had to take him sleeping. For if Roosevelt had been awake, there would have been a fight." -- Thomas Marshall
~Jones Out