You can't change the bone, but you can train your jaw muscles.
Despite wanting to highlight it, most of us don't really know what the jawline actually is. A person's actual jaw is set according to their genes (hence people's guesses to who we look like, or if our face takes after our father, mother, or a grandparent). This is known as the mandible, the bone people wish to highlight. Save for invasive and risky surgery, there is no way for the bone structure to alter itself other than a person's natural growth over the years.
What can be altered is the muscles and fat surrounding the jawline in the regions of the face and neck and that is what most treatments target. So what course do we have when it comes to them? The most common movement of the mouth is chewing (or mastication if you're feeling really scientific). Most of the methods listed as follows center around this activity:
5 ways to achieve a defined jawline
Sorted increasingly by effectiveness
(1. less effective -> 5. most effective)
1. Chew Bubble Gum
Bubblegum: Yes, long periods of chewing do stimulate the facial muscles. Many people regularly chew gum for the sake of attaining a jawline, although this method is cumbersome and yields little results at best.
However, do you really want to be chewing all day long for a minimal outcome - especially when exposure to sugar (often present in bubblegum) increases bacterial growth, raising the chance for cavities? Sure, I'll just get one that has no sugar! But be careful. There are some artificial sweeteners, such as aspartame, which also go with their risks.
2. Do Mewing
What is mewing?, you might wonder. It is what it sounds like: meowing like a cat. Okay, so maybe not.
Mewing is a technique for gradual prominence in your jawbone, using your own anatomy (mostly the tongue) to generate force across your jaw to activate rarely used muscles. It is safe, as there is no external factor to consider, except for age. The technique is not entirely simple to utilize in of itself, without considering its increasing ineffectiveness starting from adulthood. Nonetheless, it is possible, albeit tricky, to do it right without a mirror.
3. Losing weight
Predictable, but tried and tested. Except for some rare specimens, losing overall body weight is a sure-fire way to get rid of fat around your face. However, the fact remains that there are very few exercises (such as mewing mentioned prior) that target explicitly facial muscles. Besides, it may not work if you don't have enough weight to consider losing it, save for that stubborn double-chin! Relying solely on exercise and diet is good thinking, but the still not explicitly addressing the issue. Nonetheless it surely is a good additional point to have in mind.
4. Jawline Surgery
Many might consider this as final resort, after having tried a plethora of methods.
Surely surgery might grant you a slimmer, sharper jawline in a matter of weeks but there's three important points to consider:
1. It could mean quite possibly running you thousands of dollars, perhaps even above a hundred thousand in costs, especially including hihghly recommended post-op care
2. Dangers of a botched surgery depending on the surgeon's skill. You surely need a very trusted option if you choose this way.
3. It's very invasive so it surely comes with health issues. Plenty possible risks of complications - be it directly while surgery or afterwards.
Unlike the other methods it isn't natural at all so you should consider this option really profoundly and in doubt just don't it.
5. Chew Jaw Workout Gum
Perhaps the best way to get what you desire on this list, saved for the last. Jaw workout gums are a powerful tool for regular exercise sessions. By chewing on it strongly you train and increase your jaw muscles. This enforces a defined jawline and thus a more confident and sexy look.
The jaw workout gum called JAWLINER 2.0, was made to be safe, utilize your natural mechanisms in conjunction with a conscious lifestyle to achieve the best results. Just pop in the JAWLINER on alternating days (starting from the medium-soft variant) for a 5-minute workout. Chew slowly at first, holding your clenched jaw for 1 second until your muscles feel tired. This should take approximately 2 minutes. Proceed by chewing faster to really feel the burn, and finish. This would be one set. Do 5-10 sets a day, take a break on the next, and repeat. With time, as you see results and gain strength, raise the bar with the harder variant of JAWLINER 2.0