Helloooooooooooo! (the many “o’s” are to represent an echo). You can hear a pin drop in here (seriously, when the pin falls against the weight stack it makes a loud clang (clang is an example of an onomatopoeia; a word that sounds like it is spelled.)) I digress.
Consider exercise. On one hand, you have strength training. On the other hand, you have aerobic exercise (running, biking, etc). For most people, there is a big wall between the two and they are firmly entrenched on one side. Here comes the controversial part: Strength training can improve your cardiovascular system and aerobic exercise can strengthen your muscles!
In order for the body to make a positive change it has to be exposed to stresses that it isn’t accustomed to (we call this an overload). Also, we only have one brain. Our heart and lungs and muscles don’t have brains. By this I mean that those parts of our body only respond to stress, they don’t know what is causing the stress (e.g. a dumbbell or a 5K).
So here is the truth: the only way for positive changes to be made to your body, whatever the modality is this: HARD WORK. You have to work at a high level of your working capacity. There is no two ways about it, no magic pills, or special form of exercise. Just do it!