A fifth of Brits have admitted that sex is the only strenuous exercise they get in an average week. According to a survey of more than 1,800 members of the public, the majority of Brits shun exercise entirely, with time between the sheets with their partners the only occasion they ever raise their heart rate., the Daily Mail reported. But despite their reluctance to get hot and sweaty anywhere outside the bedroom, 87 per cent said they were unhappy with their physique and 74 per cent said they would like to improve their fitness. Sweatband. com''s research into the nation''s fitness habits found that three fifths of Brits don''t exercise at all. According to the results, women are less likely to exercise than men, with just a third of females questioned claiming that they exercised at least once each week compared to 44 per cent of men. Aside from sex, the most popular forms of exercise were running, cycling and swimming. ANI