Why Your 30s Are a Critical Time for Your Longevity

If you picked up smoking or drinking in your younger years, quitting by your 30s could make a big difference in your health. A new study found that these habits, along with a lack of exercise, may already be damaging your long-term health by age 36.

What the Study Found

Researchers tracked the health of people born in Finland in 1959 over 30 years, collecting data at ages 27, 36, 42, 50, and 61. They found that smoking, heavy alcohol use, and physical inactivity—especially when these behaviors accumulated over time—were linked to poorer mental and physical health. These effects were more pronounced in early adulthood.

“Both the number of current risky behaviors and their accumulation over time were associated with lower well-being and poorer health,” said Katja Kokko, PhD, research director at Gerontology Research Center and Faculty of Sport and Health Sciences, University of Jyväskylä, Finland.

Alcohol use was tied to both reduced physical and mental health, smoking to poorer mental health, and inactivity to worse physical health. The findings are based solely on Finnish participants, so more research is needed to see if they apply more broadly.

“People think that risky behavior means jumping out of airplanes or mountain biking. But it can be much more subtle than that. It can be just your lifestyle,” said Douglas E Vaughan, MD, director of the Potocsnak Longevity Institute and chief academic officer at Northwestern Medicine, who was not involved in the study.

Your 30s Are a ‘Critical Window’ for Lifestyle Changes

You might not want to think about aging in your 20s or 30s, but building healthy habits earlier in life can help you stay active and well for years to come.

“For people in their 30s, this is a critical window of opportunity to take action and make healthy choice adjustments. Making small changes now may prevent long-term damage and improve physical and mental health now and later,” Pamela Bowen, PhD, CRNP, an associate professor in the Acute, Chronic and Continuing Care Department at the UAB School of Nursing, told Verywell in an email.

Barriers like limited social support, lack of health education, or poor access to care can make it harder for some to adopt or maintain healthy habits, Bowen added. For those who can, starting early with regular exercise, a balanced diet, quality sleep, stress management, and preventive care can offer lasting benefits.

Start Now, but You Can Still Make Changes at Any Age

Don’t let the new research discourage you from making healthy lifestyle changes at an older age.

“Health can improve at any age. Research strongly suggests that people who adopt healthy lifestyles, even those in their 40s and beyond, can see improvements in their health and mood and may slow down or even reverse some damage,” Bowen said.

A study from 2023 found that sedentary people who started high-intensity interval training (HIIT) between the ages of 40 and 65 improved their biological aging by over three years. Another study found that omega-3 supplementation slowed biological aging for people aged 70 and older.

“[T]he earlier a person starts living a healthy lifestyle, the better. The key is to just start at any age! It is never too late,” Bowen said.