Buy fish, veggies and gym membership in attempt to make good on resolution to lose six kilos. Make healthy meals and work out five times a week for first three weeks. Then two times a week. Then, oh, never. Sound familiar?

Maintaining your diet and exercise enthusiasm can be the trickiest part of the weight-loss equation. But before you give in to the sweetie demon perched on your shoulder, check out these proven motivation boosters.

1. Have Lots of Sex

First off, it’s pretty damn fun. But it can also keep you on the slim track. Having an orgasm releases the same endorphins in your brain that eating chocolate does – without the kilojoules.

And research shows that the more weight you lose, the better your sex life gets: A Duke University study found that even a 10 percent reduction in weight (that’s seven kilos if you weigh 68) resulted in major improvements in all areas of the participants’ sex lives, including arousal, feelings of attractiveness and enjoyment of sexual activity.

2. Make a Promise

It’s really hard to blow off a commitment you’ve made to lots of people. For example, “joining an athletic event to raise money means if you default on your training, you’re not just letting yourself down but also the charity and everyone who sponsored you,” says Dan Hamner, author of Peak Energy.

Choose something strenuous enough that you’ll need to train seriously in advance (triathlon, anyone?).

3. Enlist Tyson

Consider adopting a fuzzy friend if you don’t have one already. Studies show that owning a dog can help you drop kilos. Why? Come rain or gale-force winds, you’ve got to get your butt outside with pooch a few times a day (unless you really want urine-soaked carpets). What’s more, most pet owners say they don’t want to let down their exercise-starved doggy at walk time. It’s another version of rule number 2.

4. Rock Out

A recent study found that women are more likely to stick to an exercise programme if they listen to music while working out. Select your workout pace, then download playlists of songs with bpms (beats per minute) that match your heart rate.

For example, if yours gets up to about 150bpm when you exercise (the mid to upper target range for a healthy 30-year-old woman), songs like the Killers’ Mr Brightside are perfect.

5. Get Out Your Sexiest Skinny Outfit

“I tell clients to take out an outfit they love and haven’t been able to wear for a long time,” says strength and conditioning coach Christopher Warden. “Just pulling it out of the cupboard serves as a visual reminder of the goal they’re trying to accomplish.”