Filming for the spy movie took place across the globe in locations including Mexico, London, Morocco and Austria, and actress Lea, who plays Bond girl Madeleine Swann, admits it was tough going from the cold mountains to the hot desert, and some of the crew suffered from the punishing schedule.
"It was really cold in the Alps and then really hot in the desert," she tells Britain's You magazine. "We were over 3,000 metres high in the mountains, so a lot of people got altitude sickness.
"Then we had to run in the desert, me in heels. I trained a lot to prepare - weights, cardio, everything. My character is a doctor, not a super-action girl, so in theory I didn't need to be that fit but I did it for myself."
Lea also shares her pride at starring alongside Daniel Craig as 007, adding, "It was a dream... I am so lucky. Every girl wants to be in a film with Daniel Craig, right? Many are probably jealous I got to film love scenes with him, no?
"We have the same sense of humour. There was a real complicity. Even when filming serious scenes we joked and had fun. It was always that 'wink, wink' feeling between us. The chemistry was strong. I hope the audience can feel that."