Charles Kennedy has admitted to being a packet-a-day smoker who is determined to kick the habit.

The Liberal Democrat leader said he only started smoking again recently after a five year break.

Within about two or three months I was back on around a pack a day

Charles Kennedy

But now he says one of his first thoughts when he comes out of Prime Minister's Questions is "it would be nice to have a puff".

Mr Kennedy talks about the vice in an interview about his health and habits for Sainsbury's Magazine.

He admits shunning the gym, getting on well with Tony Blair - who he has been able to "enjoy the occasional glass" with - and being happier in his own Scottish constituency than in Westminster.

Happy couple

He also reveals that love has changed him, that he and new wife Sarah like to eat microwave meals, and that she has helped him choose lower-fat food and to "cut back on the wine".

But in his attempts at a healthier lifestyle, it is his smoking vice that is proving the most difficult to crack, he says.

Strolling off the pounds?

"I smoked for quite a while and then suddenly stopped for five years.

"I started again - my biggest mistake - three or four years ago, just by chance.

"Within about two or three months I was back on around a pack a day.

"But I'm determined to crack it."

Election diet

Mr Kennedy says he trimmed down for the 2001 general election "and tried not to indulge in too many of my bad habits".

"I did notice, after about a year in the job, that because of the levels of activity and stress, you just burn off more calories.

"But I did also make a few gestures in the direction of proactive healthy living - eating a bit more fruit, for example, and cutting out sugar and milk in coffee."

Mr Kennedy says getting out of the Westminster hothouse and back to his Ross, Skye and Inverness West constituency is "very, very important psychologically".

My life has completely changed since I married Sarah

Charles Kennedy

"I get grumpy in Westminster when I get really, really tired. I also find that at home in Scotland is the best place to work," he said.

"In the Highlands I get more sleep, fresher air and am more relaxed and generally happier."

Mr Kennedy said his life had changed "completely" since marrying Camelot official Sarah Gurling earlier this year.

"She takes care of me, cares about my health - and my life," he said.

"She is a partner, in every sense of the word.

"Sarah makes me switch off, just for an hour or two, to go for a walk, or to chill out and enjoy a meal with her. Simple things that most people take for granted.

"Through her, I've managed to step back and realise how important they are."