As in other answers you should show that you are ready, willing and able to work long hours. Not only, you also should show that you are able to do so with the highest quality standard.
In addition, working long hours is not the hard part of the job, the hard part of the job is predictability and how it affects your personal life. You should highlight that you have a client first mentality and, when necessary, you are willing and able to sacrifice other aspects of your life to enable client success.
Finally, to not come across as a masochistic overachiever that doesn’t have anything else going on in his life and that if promoted to manager will run the teams to the ground, you should focus on how you usually recharge from high intensity periods and the importance of that. Remember most consultancies hire you to stay longer than two years so it’s important that you show that you have in you the ability to care for others who do not have the same drive and motivation but are equally good too.
hope it helps,