If you fall into the latter category, it’s time to start strength training, because cardio will only take you so far. You need strength training to maintain muscle mass and mobility. This is especially important as you age, as both men and women lose about 10% of their muscle mass per decade starting as early as in their 30s. This doesn’t mean you have to learn how to bench press, or even pick up a set of weights. Instead, you can simply use your body weight.
Article source: https://www.huffingtonpost.co.uk/entry/exercise-strength-training-weights-cardio_uk_6a8ef8b1e4b0a9d5e57bf434