According to Ace Fitness, aerobic exercise, strength conditioning and stretching for flexibility are the three core elements of all good exercise routines. A good routine builds strength, exercises the heart through increased cardiovascular activity and improves flexibility by increasing the body's endurance for muscular stretching.
Ace Fitness notes that the most important goal of any exercise routine is to increase the heart rate for at least 30 minutes per session. An ideal workout keeps the heart within 55 to 90 percent of its target maximum rate and should occur three to five days per week for health maintenance.
The Mayo Clinic also stresses the importance of aerobic exercise but notes that strength training is also crucial for maintaining overall health and fitness. A good strength-training routine can be as simple as using hand-held weights at home or doing push-ups and sit-ups. Ace Fitness recommends that strength routines include sets of at least eight repetitions to increase strength and build muscle mass.
Finally, a good exercise routine should involve various stretching exercises composed of stretches that last between 15 and 30 seconds. Both Ace Fitness and the Mayo Clinic explain that a truly thorough exercise routine encompasses each of these crucial elements.