One of the tougher leg exercises I perform are Duck Walks.  As you can imagine they are performed squatting and walking like a duck. My past exercise partner and myself used to do these at Spiece Fitness around 2013-2014 in the Sports Performance area.  You can do these anywhere you can walk so you don’t need a gym.  I’ve done them outside on grass in my backyard and even on vacation.  I believe they hit the entire lower body and my legs burn when i do them.  So give them a try if don’t already do them.     Click on the image below for a video from 2018