If your partner has recently started working out they could be sleeping with someone else, according to research.
Those who are doing the dirty on their spouse admitted their new sexual partner has inspired them to get in shape.
No doubt they are feeling self-conscious, thanks to slipping into bed with someone other than their long-term partner.
A whopping 70 per cent of cheaters revealed that their extramarital partner motivates them to exercise.
Cheaters are more likely to stay in shape while engaged in an extramarital relationship.
Comparing themselves to their new partner may well be inspiring the passion for exercise, as 71 per cent of cheaters claimed their secret lover is physically fit.
Shockingly 52 per cent revealed they consider their spouse to be unfit.
A further 58 per cent said they wished their long-term partner worked out more.
The website IllicitEncounters.com had its busiest year so far and over 120,000 people joined the site.
Are men or women more likely to be looking for extramarital affairs on the site?
According to website sign-ups, women are more likely to seek out affairs online, with 54 per cent of new sign-ups being made by women.
Fourteen per cent of women claimed that they slept with someone else to get back at their partner, while only nine per cent of men stated the same reason.
Another study claimed that one of the reasons why women cheat is that they are not being given enough gifts by their partner.
A sociologist at Missouri State University, Alicia Walker, claimed that most women do not really want to leave their husbands, despite their infidelity.