Any exercise is good for you, right? Well, broadly yes - dragging yourself off the sofa and to the gym can help reduce the risk of various diseases, improve your mental state and extend your life.
However, when it comes to exercise, there definitely can be too much of a good thing. It might seem that the more hours you spend working out, the better - but it is possible to over-exert yourself, and this can be hugely damaging for your body.
Dr Emil Hodzovic from Medichecks.com says that while obviously professional athletes have to be wary of over-exercising, don't be fooled into thinking that it can't affect the average gym-goer as well.
This doesn't mean that anyone who's done a gruelling spin class is overdoing it. Hodzovic says: "It's different from merely being tired after a good workout or aching the next day. It's when these symptoms stick around for days and weeks on end."
Overexercising isn't just going too hard in your training. Hodzovic says it is a "combination of both training too much and recovering too little".
It's also important to think of the quality of your recovery. "Staying up for three nights on energy drinks and pizza to finish an assignment or project can contribute hugely to the 'inadequate recovery' part of the equation," Hodzovic explains.
Unfortunately, Hodzovic says over-exercising is "hard to define or identify", because the line might be very different for different people. However, there are some short-term symptoms that could suggest you are taking things a little too far and not resting enough.
This includes a low mood and minimal motivation, which is particularly telling because exercise should release endorphins and ultimately boost your mood and energy levels. The same goes for poor sleep, something else that working out should help improve, if you're getting the timings right.
It also could have an impact on the quality of your workouts. Chances are, if you're overdoing it, your body will be so tired that your performance won't be as good as you're used to, and the intensity that you're able to train at will go down as a result.
Physically, it's a no-brainer that overdoing it can give you pain in your muscles and joints, as well as increase the chance of injuries.
Hodzovic says: "These are caused by a host of physiological effects within the body, some of which can be measured directly. These can include blood tests and heart rate measurements."
Exercise addiction is a very real and dangerous phenomenon. It's unsurprising really - just think of the runner's high, which often makes people want to pound the pavements more and more. Social media can be part of the picture too, increasing the pressure to fit in with unrealistic body expectations, and encouraging people to compare their own progress with others'.
Exercise addiction can also often come hand in hand with orthorexia - an obsession with eating what is considered to be 'healthy' or 'clean' foods.
As well as having a short-term impact, over-exercising can have significant long-term effects. Hodzovic describes how the constant stress on your body can change certain hormone levels, which might make it harder for diseases to be detected.
He says: "Salivary cortisol can help to identify serious disorders of cortisol production, such as Cushing's disease, but can also allude to increases in stress, including training stress."
Unsure whether you might be overexercising? Hodzovic says using blood markers for baseline readings of your hormones to see how they change over time, which can often be an indicator that you're putting your body under too much stress, can be helpful. "Heart rate variability and lying and standing heart rate readings are also used to assess recovery and over-training status," he adds.
However, Hodzovic's main recommendation for seeing if you are pushing it too hard is remarkably easy and unscientific. "One of the most effective tools is simply keeping an accurate training and performance log along with how you feel day to day, both in regards to training but also in terms of moods and feelings," he says.