Private $20,000 health clinics offering genome sequencing and full-body scans. Gyms with $40,000 annual fees. Blood plasma exchanges for $10,000 or more a pop. One-on-one sleep coaching and $300 wearables.

Pursuing “longevity” has become an expensive — not to mention time-consuming — hobby. But it doesn’t have to be: Experts say many of the practices that are most likely to extend your life are also the cheapest.

Simple lifestyle choices, like eating well and getting regular exercise, are by far “the most effective and well-supported” longevity tactics — and “nothing else comes close,” said John Tower, a professor of biological sciences at the University of Southern California Leonard Davis School of Gerontology.

The influencer-backed supplement stacks, oxygen treatments and stem cell therapies for longevity are “experimental at best,” added Joseph Coughlin, the director of the Massachusetts Institute of Technology AgeLab. If you’re looking to live longer and healthier, you’re better off doing “what science and history have confirmed.”

Here are some of the experts’ suggestions.

Work out. It doesn’t matter where.

High-end gyms might have personal trainers and fancy biometric measurements to track your heart rate and blood oxygen levels. But it’s the exercise itself that’s proven to extend your health and life spans, and you can get the same physical benefits by working out on your own, said Roger Fielding, a senior scientist at the U.S.D.A. Human Nutrition Research Center on Aging at Tufts University. Cardio exercise and strength training are both linked to lower mortality because they reduce your risk of cardiovascular disease. Just walking 30 minutes per day around your neighborhood can significantly reduce your risk; so can doing higher intensity workouts or resistance training using dumbbells at home, he said.

The American Heart Association recommends at least 150 minutes per week of moderate intensity aerobic exercise (like walking) or 75 minutes of vigorous aerobic exercise (like running or swimming) to prevent cardiovascular disease. But “any level of physical activity” is better than none, Dr. Fielding said.