Lately, I've been thinking a lot about coaching and in particular, whether or not it's reasonable to tell someone to just go for it in order to learn something correctly. It's important to realize that not everyone instinctively understands movements and people have varying amounts of coordination. How can you just "go for it" if you don't know what you're doing? Personally, I've experienced a lot of problems with this too. I need cues that I can focus on and these cues need to be good enough that they utilize normal movements I'm already used to. It's like having this limited bank of muscle memory movements, and using cues to put them together in order to learn new combination movements. Clearly there are problems with "just going for it" if you do it wrong. I can think of quite a few people who need to dial it back and learn movements slowly but correctly...

Additionally, being able to do a movement slowly or even holding a position is very differently from being able to execute quickly and strongly. There are multiple aspects that make these different:

1. You are getting totally different proprioceptive input from your muscles. Strength/velocity of contraction becomes additional sensory input that your brain must learn to interpret.
2. Different forces are acting upon the joint and/or limb. Rather than just resisting gravity, you have to resist your own momentum. This means that you need to activate antagonistic muscles to decelerate and, once again, that means more new sensory input and the need to control more muscles. 
3. You're recruiting and training different muscle fiber types. 
4. Eccentric contraction vs isometric contraction.

Just inherently, it should be obvious that holding a position vs stopping a movement are two very different actions.

I also really need to learn to stay calm so I can use my brain when I argue. The instant I get angry or upset, it's like science leaves u my brain and I don't know how to make evidence-based arguments, haha.

Lastly, I have a huge problem with the attitude that you have to "overcome your body's weakness" or anything that's similar to "no pain, no gain". If someone is struggling, to tell them that they aren't trying hard enough is an incorrect response. It's important to recognize why a person might feel uncomfortable with doing a move or hesitates to do it quickly. Confusion or hesitation during a dynamic movement is dangerous.