trying to be 100% effortless with the arm and just let the body do what it wants. in this session, I'm not caring about shoulder rotation, over-rotation of the hips, leg swinging around, getting more convex and deeper into the hit. I am focused on just having the swing feel like it's at the hit and not "completing" the swing, as doing this will shorten my follow-through to look more like Federer's. I have 0 muscle activation in the arm or hand (or body really), everything is being generated from the hip and I'm just letting everything go and do what it wants. i also focused on getting the hips out earlier (i.e. uncoiling when the ball is landing). this helps with the sequencing and rhythm and makes sure the racket doesn't get "stuck" (i.e. not getting convex by the time it comes to make contact with the ball). being this loose, your hips need to get out earlier. getting the hips out early makes it feel like you have 2x the time to hit the ball. i also focused on feeling the "pause" of the racket right before the hit. this pause feeling helps it feel like i have another 2x time to hit the ball. in total, i then felt like i had 4x time to hit the ball, it was crazy how much it felt like time slowed down, even if i was getting the ball smacked at me on the baseline and having to hit a full swing pickup. i made sure to release all muscle tension in my face, as this helped my body to remain 100% relaxed and effortless. getting the hips out early + feeling the "pause" was critical to sequencing everything. making sure my hand muscles were completely relaxed and limp was important to getting the strings to face downward as well as not letting my racket go concave too early (i.e. losing the lag and racket face closing too early rather than letting the strings stay open long enough to really absorb the ball into the string bed and hit it with effortless power). in the post-contact part of the swing, i felt the racket yank and pull me, which is why the huge shoulder rotation at the end of the swing. since i didn't want to restrict anything, that is why you'll see some of my swings where it looks like i rotate my shoulders a crazy amount. this of course is a bit of an exaggeration of the feeling of not restricting anything and being totally 100% loose and effortless, but it definitely helped my swing look more like Federer (in the finish and just by allowing me to unlock a new level of effortlessness). I felt balanced on every single ball rather for the 4 hours we hit, never feeling like my body was pulling off the hit while my arm was stretching out to the 45°. when i wanted to get more topspin and get into the vertical, i made sure to feel like i was swinging across the ball and staying more behind the 45°/sine wave plane. for my backswing, i felt like i was just expanding straight out to the hit, not back or even back at an angle, just straight to the hit. this is probably why my arm gets straighter earlier than Federer's in the backswing and the swing towards the ball. if i were to hold this off or feel like the arm remains bent while expanding to the hit, i will probably look more like Federer and the racket whipping back will happen a bit later and more in front like Federer. I could also attempt feeling like the hit is more in front, but i don't think that will do it. The other differentiation between our two swings is his non-hitting hand. when the racket starts swinging to teh ball, my non-hitting arm and hand retract in and up while his stays wide. If i copy his non-hitting arm, my stroke will look prettier.