Hyperbaric oxygen therapy is a cutting-edge (but costly) longevity treatment. A doctor who researches it said to focus on free lifestyle changes like exercise first.EXTREME-PHOTOGRAPHER/Getty ImagesA high-tech treatment called hyperbaric oxygen therapy may boost longevity and performance.A longevity doctor said you should first focus on the basics of living longer.The best longevity habits, from exercising daily to building community, don't cost a thing.You may want to hold off on paying for the latest trendy anti-aging treatment — some of the best ways to extend your life and health are free, according to a longevity doctor.Dr.