So you're mourning the loss of the weekend warrior you were in your 20s. Never fear. The decade of the 30s is also a good time for remarkably good health, especially if you took care of yourself in your 20s.

If you missed a few things — like blood pressure and cholesterol screenings — it's never too late to start being healthier today. If you're a man in your 30s, avoid these mistakes.

1. You think you don't need to stretch

You absolutely need to stretch and that goes for anyone of any age. Just because you're as buff now as you were a few years ago, it doesn't mean changes aren't happening. If you don't watch it, that six-pack can easily turn into a no-pack. Plus, men's bone mass begins to decline after age 30, and that can lead to fractures later in life, according to the University of Utah.

Since your career is taking off, you're probably siting at your desk more, and that's not good for your health, either. Many studies show sitting too much raises not only your risk for obesity, heart, and cancer, but also reduces flexibility, which could potentially mean disabilities later in life, says family medicine physician Dr. Rick Henriksen of University of Utah Health Care.

Unfortunately, many of the workout routines younger guys do, such as weight lifting, could hone muscles, but don't help much with flexibility, which adds to the problem. "A lot of younger men wind up with bad backs and other musculoskeletal issues well before midlife, since they don't mix up their workouts," says Dr. Henriksen. Despite your robust health, by the time you reach your mid-to-late thirties, you will also lose some aerobic capacity, and that means loss of strength, he says.

If you haven't established a regular exercise routine that includes a mix of aerobic, strength and flexibility training, start now. Although you're in good shape (hopefully), remember that starting at about age 30, men burn about 12 fewer calories per day. Though it doesn't sound like much, pounds can add up quickly if you don't start eating smarter, too, according to the University of Utah.

2. You think men don't get stressed out

The 30s bring on new stressors for both men and women. Careers are taking off and you need to work 40-plus hours a week just to be noticed. Maybe you got married and have a little one at home and just can't seem to catch enough sleep.

But, in general, women talk about these kinds of issues and may be more adept at stress-busting behaviors. Men just suck it up. "Men withdraw and don't talk about things, and if they're really stressed it just gets worse," says internist Dr. Steven Lamm, director of the Tisch Center for Men's Health at NYU Langone Medical Center. "They don't recognize that too much stress can lead to other mood disorders like depression."

Men may also exhibit symptoms like binge drinking and anger, for example. All this angst can lead to a host of potential problems including heart disease, cancer, sleep disorders and erectile problems, among others. Men are also at higher risk of suicide than women.

The good news is that men benefit from the same "de-stressors" as women do, like exercise, sleep and good nutrition. The first step,

though, is to get men to recognize there may be an issue, says Dr. Lamm, and if you're having anger issues, can't seem to get a good night's rest, or having potentially stress-related problems in the bedroom, see a doctor.

3. You think you're too young to need a doctor

You said the same thing in your twenties!

Aging — even in your thirties — brings some inevitable changes to your body. So, if you haven't dragged yourself into the doctor yet, consider going to see someone just for a "once over," says Dr. Henriksen, emphasizing that in most cases an exam will reassure you that you are fine, but will also help pinpoint areas that you may need to be aware of based on family history and lifestyle, for example.

Here's the minimum you need to do: Get your blood pressure checked and get a cholesterol screening.

"A lot of times, guys will look great and feel great, but we find out they may be at risk for heart disease or diabetes down the road," says Dr. Henriksen, assistant professor of family and preventive medicine at University of Utah School of Medicine.

Also, about half of all cases of testicular cancer are found in men ages 20 to 34, according to the American Cancer Society. Although the disease is relatively rare and there is no standard screening for testicular cancer, doctors may discover it during a physical exam — which is one more smart reason to see a doctor.