GPP is very important. Mine was going down as I got stuck in the house too. I have subbed out tires and sleds for walking for now.
Walking is perfect for GPP. Find hills, use extra weight, but most of all just feel rejuvinated from it. Not worn out.
In the gym you can grap a fixed barbell like they use for curls. Just set it on the floor, grab one end of the weight and drag the other. This will work with a regular bar too just make sure you have a GOOD clamp for it.
You can also use those "blast straps" if your gym has them and just hook them to a plate and use it like a sled.
Using a low cable like a sled works to. You will only get a couple steps out before it hits the top but then back up with the same form you walked out with. Its very different, as if you are pulling the sled and then it pulls you back.
Grab a plate and hit the treadmill. Front carry it, hold one in each hand, whatever. Good for stair master too but watch yourself.
Crab walk, bear walk, or whatever you can figure out is all good stuff. Just remember this is for recovery and increased work capacity, not to max out.
Hope this helps!
