Besides your sense of sight, there is another sense that tells you what position your body is in. That sense is called your muscle sense. Suppose, for example, you wanted to climb a tree. Your eyes would tell you how high up the first branch is, but then your muscle sense takes over and decides how far from the ground you have to jump to reach that branch. Here’s how that happens.
Your muscle sense is ruled by special nerves called proprioceptors. These proprioceptors, which are found in your muscles, joints, and tendons, respond to pressure and tension. So, by reporting to your brain what these muscles, joints, and tendons are doing, the brain can then make you aware of the position your body is in and then guide you in what to do next, how much to crouch and how far to jump to reach that first branch.
Your muscle sense also helped you when you were learning to swim and to play ball.