There are several idle, walking, sitting, etc animations posted by some of the excellent mocap artists (Cuddle, Kitty, Timbo, etc).
But, if you like the built-in, it is possible to record the built-in animations with timeline.
Just set up the desired animation sequence, then in timeline add the controllers you want to record, activate animation and hit record.
You can usually get away with just recording head, hands, feet, hip but can always add more if it improves realism.