Whether you're training movement for rehab or athletic performance, moving with "attention" and "intention" makes a huge difference in terms of motor learning. For example, doing an shoulder raise exercise with a weight or elastic tubing will help strengthen shoulder muscles as resistance and gravity place physiological demands on the muscles. However, strength gain may not carry over to actual functional tasks such as reaching arm overhead to put a dish on a top shelf, changing a light bulb, or any overhead throwing, which means there's no motor learning.
Exercising just for the sake of strengthening or stretching muscles will not require much attention of the brain. There won't be much learning without the engagement of the brain. Adding an "intention" for movement/exercise will add a meaning and purpose to movement, and this will grab the brain's attention. Here are examples. When boxers do shadow boxing, they have clear intention of every movement, that is fighting against an imaginary person. During Aikido practice, an attacker has a clear intention when he/she is grabbing the opponent's wrist, that is to keep him/her from reaching for their weapon. This intention organizes the bodies to create movement.
You wouldn't exercise for no reason, would you? You probably exercise to improve your functions. So, think about what specific function you're trying to improve with each exercise. Once you know that, you visualize a specific function while performing each movement.
In order to make real improvements that will last for a long time we will need to change how we move. When we change how we move, we'll start to place demands on our bodies differently so we'll start to use muscles that we didn't used to, which then over time will become stronger and more flexible. When you move with intention, you will pay more attention to your movement, and your movement becomes much more purposeful and meaningful, which will make your exercise much more effective. Strength gain is given when you place demands on your bodies, but motor learning (changing movement habits) isn't without attention. Next time you work out or practice movements, think about what specific function you are trying to improve with each exercise and practice moving with attention and intention.