If you plan on playing the entire game, you will definately get this one by the end. Even if you ride around in carts as much as possible, there is enough walking, jumping, etc during the missions that you will get this without even trying.
Pressing / Holding the [RB] will make Larry sprint for a short amount of time. I always just hold this down and keep pressing it to get Larry to his destination as quickly as possible. You should easily be able to complete the entire game (less collectibles and side missions/races) in about 5 hours. Well under the 8 hour mark for another achivement.