This is a really good question given that there has been such heavy emphasis on “aerobic” or cardio training for the last several decades. It’s not that an active lifestyle and more demanding cardiovascular exercise isn’t important, but if it comes at the expense of proper resistance training, it is a big mistake. Most exercise guidelines (ACSM, AMA, AHA, CDC, etc…) now recommend twice weekly resistance training for most healthy adults. In addition, properly performed resistance exercise is the only way to improve all of the following: muscular strength and endurance, bone density, cardiovascular fitness, and flexibility. There is no other form of exercise that can stimulate such a wide range of physical adaptations. Not all resistance training is created equal, however, so learn proper lifting technique first and then gradually increase your effort as your condition improves. Seek guidance from a well-qualified personal trainer, if necessary.