The popular fitness certification known for its focus on personal training is the Certified Personal Trainer (CPT) credential offered by organizations like the American Council on Exercise (ACE) and the National Academy of Sports Medicine (NASM). This certification prepares trainers to design individualized fitness programs, assess client needs, and provide proper guidance during workouts. Gaining certification ensures that trainers are knowledgeable about exercise science, nutrition, and client health, allowing them to effectively support clients in reaching their fitness goals.