Adults over 40 may not need to spend hours in the gym to maintain muscle, preserve mobility and stay strong.According to Los Angeles fitness entrepreneur Carl Daikeler, just 10 minutes of targeted resistance exercise each day can help preserve muscle, mobility and long-term function.Daikeler, 63, who has spent 28 years leading BODi, the fitness brand formerly known as Beachbody, says his approach to exercise stems from a practical desire to stay healthy without having to be a dedicated fitness enthusiast.4 SIMPLE HABITS CAN HELP SLOW MUSCLE LOSS AS YOU AGE, FITNESS EXPERT SAYS"I don't like to eat healthy, I don't like to work out," Daikeler told Fox News Digital at the Strong New York conference in September."I'm just constantly trying to figure out how I can hack my way without having to overturn my life to become one of these diehard health and fitness people, because I'm never going to become that."While resistance training builds muscle and strengthens bones and connective tissue, cardiovascular exercise challenges the heart and lungs, helping to maintain overall fitness. (iStock)For adults looking to stay healthy in midlife, Daikeler recommends what he considers a "minimum effective dose" — short, targeted resistance workouts at home instead of lengthy gym sessions."Ten minutes a day, and you can establish and build and maintain muscle," he said.WANT TO AGE BETTER? RESEARCHERS SAY 4-MINUTE ROUTINE MAY HELP PREVENT DANGEROUS FALLSFederal physical activity guidelines say that adults should perform muscle-strengthening activities involving all major muscle groups at least two days per week, in addition to regular aerobic activity.Rather than doing a full-body workout every day, Daikeler recommends rotating muscle groups — focusing on the chest one day, upper body the next, then legs and glutes — to build consistency without requiring lengthy gym sessions."Ten minutes a day, and you can establish and build and maintain muscle.""Do that consistently, and yo...