What was the appeal of this role?
I really wanted to do an action film and The Guardian was a complete departure from anything I had done before. I was also looking for the chance to work with actors who I could learn from; who I could look up to. It was great for me to get the chance of working with Kevin Costner. I have always admired him and been a big fan. He has always been a hero to me since I saw his film Field Of Dreams. I learned so much from him. Also it was great to do a film about the Coast Guard, because their story has not really been told before and they do such an amazing job. When I read the script, I hadn't heard a lot about what these guys do, which was shocking. It was a gift to me to spend time with these individuals and get to know them as people.

How did you prepare for this role?
You cannot really fully prepare for a role like this, it is very challenging. You have to grin and bear it. I went through the script and found out I had to hold my breath for three minutes in one scene, I would have to tow somebody through the rough water and I would probably have to do it 20 times. But when it came to filming, the pain and discomfort was not a bad thing, because it made it easier for the character to seem real. You are wet and you are very cold all the time, so you don't need to act it, it's one less thing to think about. The swimming scenes were tough but that made the scenes where we were not wet and cold really nice, a great relief.

Is it true that you could not swim before taking this role?
I could barely swim. I just don't like the water much. I do not like taking a bath. As a kid growing up in Iowa, I learned to swim, but it was not real swimming. I could get in the water and just about make it to the other side of the pool. I was trudging through the water, that's very different from crossing the pool in eight strong, smooth strokes. Swimming the way I learned for this film is about being efficient with your oxygen and swimming in comparable times to Olympic swimmers. That's the level I had to achieve. These guys dedicate their lives to saving people in the water and I had to make them look like studs.

How much training did you do?
II trained for eight months, before we even started filming. I couldn't just be good; I had to look like I was the best of the group. I made sure I could do everything the Coast Guard swimmers have to do to get through the program. I quickly realized how unfit I was, so I quit smoking immediately, I said 'that's it' I was smoking one and a half packs of cigarettes a day, When I realized I would be working with Olympic swimmers, I said to the director Andy Davis, 'You can't do that to me.' So I started swimming every morning in a lap pool and swam from one end of the pool to the other and then back. It took me forever and I was exhausted. I had to build up my speed every day. The first morning I swam one length, from one end of the pool and then back and it took me forever. I was beat - totally exhausted.

How did you motivate yourself to improve?
I looked over at the other side of the pool and there was a guy who was 75 years old and he was lapping me - lap after lap, there was no way I could keep up with him. And he kept going and going for the hour swimming back and forth. I swam from one end to the other and I was done. I could not breathe I was so tired. So I looked at this guy and I panicked, thinking 'how am I going to do this?' But the guy provided a benchmark for me to judge my progress. And I trained hard at 6 o clock every morning. After a month and a half I was even with the guy and then a month and half after that I really started going faster and taking him, sprinting.

It must have been different training in the ocean?
That was a completely different thing. I was throwing up constantly and I would keep going. Every time I threw up I would go back in and swim more. It was physically exhausting. After the initial training, I had to go through boot camp with the other actors (and Olympic swimmers and real Coast Guard guys) who were in the film with me.

What was the boot camp like?
It was really tough. I had to ask these Olympic swimmers I was training with, to go slow, to take a notch off their speed. A couple of times I said 'Guys I'm supposed to win this race.' But they helped me a lot and showed me how to swim better. It was very challenging. I have never been yelled at so much in my life, except perhaps by my parents. We often had to do 50 push-ups. And the Coast Guard guys running the training program did them with us, so I have great respect for them. For one scene, I had to sit down under the water for three minutes and it tested me. I can tell you.

Did you feel at any point that you couldn't go on?
Well it was grueling. But I am very determined. The idea of stopping the action in the middle of a take and going 'I can't breathe, aaaggh...please I need help'. That was not going to happen. I wouldn't let them see me suffering or in trouble. After we cut I would say 'I just need a minute to recover', I'd take the minute, then jump back in the water. How did I do it? I refuse to fail. I have to win, I believe it's not what you achieve in life it's what you overcome. My desire is always to reach for the next rung on the ladder.