I'm going to talk you through how to do a walking lunge. Now if you don't have a whole lot of space, you can still do the lunge moving forward and moving back. And if you have the space then you really want to walk with it. I'm going to show you what you want to think about mechanically with the lunge.
The first thing is just to take a big step forward. If you don't take a big enough step, you're not going to end up in a good lunge position. You want to end up in a solid lunging stance, kind of like a 90 degree angle with that front leg and that back leg, depending on the range of motion that you have in your knee.
From here you're coming up, and if you can just hold your balance for a second. Feel that stability of your standing leg, so if you hold the balance it's a little more core work, engaging the glute muscle. You're working on stability in the ankle joint. And then take another step, coming into the lunge. Bring it back up, balancing, coming down, and then bringing it back through.
You could also just move continuously and not balance. So stepping and just constantly traveling forward, right from one lunge to the the other. A big mistake that people make with the lunge is allowing the front knee to shoot forward, too far past where you want it. That puts a lot of stress on the patella.
So even though you're moving forward, you still want to go straight down into the lunge. Come up, move forward, but bring yourself into that center position, not actually allowing the knee to go forward or the spine to go forward. Keeping a nice neutral posture, keeping the core engaged, and then a great work out for the lower body.