If, like so many of us, your New Year's resolution is to get healthy and lose weight, it can be all too tempting to exercise like crazy in an attempt to reach your fitness goals as fast as you can.
While being active every day is always a good thing, doing too much too soon is detrimental to your health, and may take you further away from your ideal body.
Wollongong personal trainer Brendon Smith, from the Vitality Fitness Centre, sees many clients at this time of year keen to undo the effects of too many drinks and nibbles over Christmas, but says those who achieve the best results are the ones that take it slow.
"Quite often people have their holidays and the first thing they'll do when they come back is jump straight back into their old routine at the same intensity before their break and it's common to see people crash and burn after one or two sessions," he says.
Overtraining can result in overuse injuries, feeling lethargic and even fat gain - the opposite of what you want to achieve through exercise - though the problems that arise will depend on what kind of activities you do.
"If you're a cardio person, if you overtrain you'll tend to develop long-term overuse injuries and a feeling of sluggishness or uselessness," Smith says.
"The reverse is almost true for people who do explosive exercise and heavy weights: they find themselves quite restless and unable to sleep during their downtime. I've had that happen to me; it's almost a feverish sleep, and that's always a sign you've gone too hard and should take it down a peg or two."
Recovery time, including a good night's sleep, healthy food and breaks from activity, is just as important as the exercise itself.
Smith says there is nothing wrong with going for a walk or to a yoga class in the morning and following up with strength training in the afternoon, because the activities are of different intensities, but training at high intensity several times a day isn't good for you.
"The big thing is to be in tune with your own body," he says.
"If you're waking up tired and feeling sluggish, you should think about having a rest day and turning down your regime. If you're bouncing off the walls and feeling good, do what you have to do."
His advice for those getting back into a regular routine after the holidays is to take the intensity down a level, train for shorter periods, and don't expect to be capable of the same routines straight away.
"I tell my clients to leave their ego at home and come in and reset," he says.
For those who are rebooting their fitness regime after years of inactivity, it also pays to be wary of not expecting to do the same exercises you could in your 20s.
Smith says the best results are achieved gradually, giving you time to form habits that will help maintain your weight and fitness.