Have you ever decided to get fit? But then you found you really couldn't be bothered? This often happens when you don't set a specific goal. Without a reason to exercise, most people struggle to get started.

Heidi Howard, a 30-year-old Brisbane mum, had vague notions that she wanted to get fit and lose weight in the 18 months following her baby's birth. It wasn't until February this year that she created a specific goal. She decided to lose 7kg by the time she went overseas in July. She started getting out of bed at 5.30am to attend personal training and boot camp classes. She wouldn't have done that without a firm goal in mind.

Personal trainer John McPaul from Energyzone explains, "Just having something to aim for, you increase your commitment and your desire to achieve something. You're more likely to get results that way. And you're more likely to make the sacrifices to achieve your goal."

The four Ps

When you set a fitness goal, keep the 'four Ps' in mind.

1. Personal
Make sure your goal is personal — one you've chosen for yourself. You might get some input from a personal trainer or a family member but ultimately it needs to be something you feel emotionally attached to.

2. Present tense
It helps to write your goals down, and pin them up on your fridge or wardrobe. John suggests writing in the present tense, to make it feel realistic and attainable. For example: "I feel so proud of myself as I'm crossing the finish line of the Bridge to Brisbane fun run, in a time of one hour 20 minutes."

3. Pinpoint a date
"You're more likely to achieve a goal if you have a specific date in mind that you're working towards," John says. "It puts on a bit more pressure."

4. Pay day
How will you reward yourself once you've achieved your goal? You might go shopping for new clothes once you hit your goal weight. Or maybe you'll have a weekend away after completing your triathlon. Keep that reward in mind right from the start. It'll give you another reason to stay motivated.

Break it down

It can be overwhelming if your goal feels a long way off. So you might need to break it down into daily, weekly and monthly goals. "Let's take someone who's wanting to lose 25 kilos over the course of a year," John says. "If you break that down into half a kilo a week, or less than 100 grams a day, then it doesn't seem as unrealistic."

Move the goal posts

Our Brisbane mum Heidi has lost 6.5 kg and is on track to achieve her goal weight before July. "After about 12 weeks there was a bit of a shift in motivation," she says. "It wasn't just about losing weight — it was about maintaining fitness. Now it doesn't matter to me so much what I weigh, because I feel good and my clothes fit." Heidi has recharged her motivation by setting a new goal. She's aiming for a 5 km fun run at the end of June with some girlfriends.