I've heard about the mind-muscle connection a lot but I just can't seem to understand it enough to get it to work. I get that you are supposed to mentally focus on the muscle, but I don't really feel any difference. For example, I have a hard time feeling pull-ups in my back and trying to focus on my lats while I am pulling up doesn't really activate them. Are there any specific techniques that would increase this connection? And what about compound exercises like the back squat, what muscle(s) should I be focusing on then?
Here are some tips that helped me:
Know your musculature: The 'back' is an ambivalent term that includes roughly the lower back (erectors), lats, traps, rhomboids, rear delts etc. So when you do a pull up there's a good chance you're using a lot of other muscles to compensate for weaknesses in other muscles. Likewise, when you're hitting legs, you have calves, quads, hamstrings, glutes, adductors etc. Depending on how you're squatting you could be hitting those muscles differently. Try different exercises that actually hit those muscles specifically so you know what the burn in that area feels like. This helps you for that mind muscle connection. The back squat with free weights is an exercise that involves you bracing with your core, using those minute stabilizers, glutes, quads and hamstrings.
Make sure you're doing the correct exercise at a manageable weight.For pull ups to hit lats, try doing assisted pull ups, with your chest puffed up and pointed out. Really feel the lats contract and stretch. Don't cheat either, because if you are, it means your lats aren't strong enough and you're using arms and or momentum to pull yourself up instead of your lats. To further develop a mind muscle connection with your lats, try lat pull downs and standing lat pushdowns. You might not have much lat development in the first place for you to 'feel' the lats. The connection comes with constant training and practice.
Ask a friend to poke or touch the part of the body you are trying to engage with the appropriate exercise at the appropriate weight as discussed above. Lots of physical trainers and IFBB bodybuilders use this with their clients to help them zone in on the muscle they're trying to target.
Watch people who know what they're doing on youtube or ask experienced people at your gym for help because lots of people gather tips/cues over the years as they train.
Something else you can use to help you search up tips is the word 'cue' online. Google cues that help with the various muscle groups you're trying to target along with their appropriate exercises.