When it comes to healthy living, there's no shortage of competing views on how to fight flab, run faster, sleep sounder and feel happier.
But what if when you exercise - and eat and sleep - is just as important as how?
Mounting evidence suggests our bodies perform differently at different times of the day. Like all living things, we have an internal clock that affects our hormonal responses, body temperature, heart rate and sleep cycles. It's determined by something called circadian rhythms, which follow the 24-hour pattern of Earth's rotation.
Health experts say that knowing your body's clock can help you synchronise your daily activities for optimal health. Mastering these internal rhythms can pay dividends - from controlling your weight to sleeping better to improving your overall mood.
"Whether you are a yeast in beer or a fly or a dog or a fish, we all have this innate 24-hour circadian rhythm," said Dr Michael Howell, a neurologist at the University of Minnesota.
"What your body is doing at eight o'clock in the morning is different than what your body is doing at 10 o'clock in the morning. Your gut responds differently to food at different times of the day, and we have different capacities for exercise at different times of the day."
For many people, a good night's sleep is the hallmark of optimal health.
There's no perfect time to wake up, Howell said, because sleep cycles vary dramatically from person to person. But finding the time when you naturally wake up is crucial to getting good rest.
Night-time, Howell said, isn't the only time our bodies crave sleep. Our energy level and body temperature take a natural dip in the middle of our waking day, making us tired. Before industrialisation, most people did not work a conventional eight to nine hours in a row without pausing for rest, he said.
Although most modern work schedules do not make it possible to accommodate a mid-afternoon power nap, the most refreshing sleep comes from having slept six hours at night and then napping for up to two hours in the afternoon, Howell said.
Some physiologists back up the idea that afternoons are the perfect time to tackle high-intensity exercise.
"That's because you have the day to warm up as opposed to waking up with stiff joints, and blood flow (in the morning) might not be quite what it is at the end of the day," said Paul Mellick, an assistant professor in the Department of Health and Human Performance at the University of St. Thomas in St. Paul, Minnesota.
When it comes to eating, experts differ on timing.
"From a scientific standpoint, there have been studies that say eating smaller meals, more frequently, can be beneficial. So, eating every two hours," said Katherine Zeratsky, a registered dietitian with the Mayo Clinic in Rochester, Minnesota. "There's equivalent research that says eating three meals is adequate."
But they're unanimous on the importance of breakfast. It keeps your mind sharp and can prevent overeating later.
Early risers stand to benefit from several wellness pursuits timed perfectly for the morning hours.
Erik Storlie teaches meditation at the University of Minnesota's Center for Spirituality and Healing, where his students often ask: "When should I meditate?" He tells them they must find their own optimum time, but generally, one of the best times is when you wake up - when the world is quiet. He also suggested pausing in the middle of the day, and just before you lay your head on the pillow at night.
The body's inner clock can even help you perform better in other, more surprising, wellness areas.
Levels of oxytocin, also called the "love hormone," are highest in the morning hours. Men's testosterone levels also peak early in the day.
When it comes to having great sex, it seems, everyone should be a morning person.