Cancel the gym membership and send your kids/flatmates out to get milk - according to scientists, sex counts as 'significant' exercise.
This comes as good news to those of us who hate gyms or have been vacuuming the house a bit too vigorously to shed the festive season pounds.
Researchers, reported The Daily Mail, "found that men burn 120 calories from half an hour between the sheets, while women can lose 90 calories."
For most of us, that's the equivalent of a 15-minute jog.
In the study, scientists from the University of Quebec in Canada looked at 20 heterosexual couples, aged 18 to 35, and asked them to have sex once a week for a month.
"The subjects, who were also asked to jog on a treadmill for 30 minutes, were fitted with armbands to measure how much energy they were expending and fill in questionnaires to record their enjoyment."
Aside from the findings of the study, there are plenty of other health benefits of sex, ahem, other than cardio.
Research from Scotland revealed that people who had sex even twice a fortnight managed stressful situations better.
WomensHealthMag.com reported: "That's because endorphins and oxytocin are released during sex, and these feel-good hormones activate pleasure centers in the brain that create feelings of intimacy and relaxation and help stave off anxiety and depression, says WH advisor Laura Berman, Ph.D., an assistant clinical professor of ob-gyn and psychiatry at the Feinberg School of Medicine at Northwestern University and author of It's Not Him, It's You!"
The number of calories each person burned was recorded, as well as their metabolic equivalent of task (MET). This is what measures an activity against sitting still, which is called 1-MET.
In the end, the results showed that men burned on average 4.2 calories a minute, compared to 9.2 on the treadmill, while women burned 3.1 calories a minute during sex and 7.1 jogging.
The study also recorded an average 6-MET for men during sex and 5.6-MET for women, roughly the same as playing doubles tennis or walking uphill.
"These results suggest that sexual activity may potentially be considered, at times, as a significant exercise,” said lead author Julie Frappier.
"Moreover, both men and women reported that sexual activity was a highly enjoyable and more appreciated than the 30 min exercise session on the treadmill. Therefore, this study could have implications for the planning of intervention programs as part of a healthy lifestyle by health care professionals."