For Christians, Lent has arrived and along with it, millions of people sacrifice something seemingly important to them for 40 days between today, Ash Wednesday and Easter Sunday. For Matt Sullivan, the character played by Josh Hartnett in 40 Days and 40 Nights, that seemingly important sacrifice is sex.

Hartnett became a huge star after the blockbuster, Pearl Harbor and was soon one of the busiest actors around. He was consistently cast in dramas, thrillers and horror films so when this particular comedy came his way, he was excited and nervous to switch gears.

Michael Lehmann is the director of 40 Days and talked to Spliced Wire about how great Hartnett's comedic performance was in the midst of doing more serious fare.

I think he did a good job. That was a tricky performance for him because he's not a comedian, he's not a "Saturday Night Live" kind of comedian, and he has to carry a comedy. I don't think he realized going in how hard it is to do comedy. The pressure is on you. If you do a drama, you kind of know when you've (shot a scene) whether it works or not. In a comedy, at the end of the shooting day, you have no idea. Josh would say, "Is this gonna be funny?" And I'd say, "Josh, you can take my word for it, it's gonna be funny."

So his approach -- which I really think was the right one and I encouraged him a lot -- was to just play the character true to who he would be in a situation and let the humor flow from that. Obviously he worked a lot on how to physically show the frustration. But he's good. I mean, he surprised me with how good he was at pulling this stuff off.

During post-production, Hartnett, still self-conscious about his performance, continued to check in with his director who repeatedly kept telling him, "It works! You're great! You'll be happy. You'll be surprised. I really wish you could sit down in a theater full of people and hear them laugh."

After the film's release, Hartnett spoke to the BBC about working on the film, this genre and choosing his work.

I look for the character to be something interesting, the script to have a good story and be original, and a director that I admire...The comedy wasn't easy for me. I'd never done it before so it was a real challenge for me. I thoroughly enjoyed it though and would definitely do another one.

40 Days and 40 Nights is now available on DVD, Blu-ray and Digital Download.

Check out some of Hartnett's other films including The Faculty, O (Othello), Halloween H20, and Sin City.