In our 20s, we may not think that much about our bodies. Why bother when most of us are pretty healthy? Our bodies tend to do what we want them to do with ease. But, taking good care of our bodies more in our 20s, may help us stay fit in our later years. Your body is already aging even if isn’t visible. Eating well and exercising are great places to start, but there are also specific ways to keep yourself in shape to enjoy this decade and all the decades to follow.

What’s happening in your body in your 20s?

Your brain

As we age, our bodies often gain weight, but our brains lose weight. Our neurons, or cells in our brains that transmit information, begin to decrease in our 20s. Then, our brain begins to shrink around five percent per decade after age 40. According to the National Institute on Aging, as certain parts of our brains shrink, mental function and memory is affected. It becomes more difficult to multi-task and recall of words and names may slow. Blood flow can decrease while inflammation will often increase.

What can I do?
Stay active and stay rested. Doing a crossword puzzle, taking a walk, and meeting up with friends are all activities that can help the brain to stay “plastic” — able to adapt to new challenges. It shouldn’t be go, go, go all the time, though. Our brains also need sleep. According to a study published in 2014 by the Center for Sleep and Circadian Neurobiology at the University of Pennsylvania, staying awake for too long can also damage our neurons, the locus cerulean (LC) neurons to be precise, which help keep us alert.

Your skin
Environmental and lifestyles choices can have a big impact on skin. And while those outside forces are putting their stamp on us, forces inside are also making their mark. In our 20s, the body starts producing less collagen, the protein that gives our skin structure, and less elastin, which gives our skin, as the term suggests, elasticity. Cell turnover slows, resulting in thinner skin so it takes longer to heal from wounds and bruises. Sun-damaged skin, however, appears thicker. Some of these effects won’t visibly appear until your 30s, but by that time the process will have already started. Eventually, more than 90% of older people will have some kind of skin condition, including age spots, wrinkles, warts, and skin prone to frequent bruising.

What can I do?
Use an SPF moisturizer. We all know it: the sun can damage your skin. But some days we might not want to bothered with sun protection. Moisture is also vital to keeping skin looking and feeling its best. Take the advice of the American Academy of Dermatology and double your skin protection by using a moisturizer with SPF every day. Yes, even in the winter. We may not be able to see all of the sun’s rays, but they can still get to our skin and accelerate its aging.

Your lungs
If you’ve never been a smoker, you might think your lungs have nothing to worry about. Instead, as early as our 20s, our lung capacity starts to shift. As we age, our bones are thinning and changing shape. This means the bones of the ribcage are also changing, affecting the expansion and contraction the ribcage does to accommodate the lungs. The diaphragm, which supports breathing, weakens with age, as do the muscles and tissues that keep the airways open. According to the American Lung Association, with changes in the nervous and immune systems, as well, exposure to smoke and air pollution is more difficult to clear from the lungs and more difficult from which to recover.

What can I do?
Don’t smoke or stop smoking if you do. Cigarette smoking causes lung cancer and the chronic obstructive pulmonary diseases (COPD) of bronchitis and emphysema. Smoking narrows the air passages, making breathing more difficult and destroys vital lung tissue. Do your best to also reduce your exposure to environmental air quality hazards, as well, like pollution from cars and factories.

Being more mindful of how we treat our bodies in our 20s can bring benefits as we age. If you can establish healthy routines now, like not smoking and using SPF, you might be able to cut down on the doctor’s visits later. Enjoy your 20s, but don’t sacrifice your health in the process.

Camille Acker is a freelance writer living in Chicago and is a co-founder of The Spinsters Union. She is the proud owner of many, many books. See more at camilleacker.com.