Walking lunges have not been tried and found wanting; they have been found difficult and not tried.
I borrowed this quote from G. K. Chesterton. Okay, he didn't really say this about walking lunges; he said it about Christianity. But up until 2008, in my case at least, it had been true about lunges, walking or otherwise. Here is what a walking lunge looks like:
My coaches cause me to do three sets of twenty per leg, alternating between the left and the right leg. I have a love/hate relationship with them. I've always avoid doing lunges because, as Chesterton noted about Christianity, they are difficult! At first, I couldn't even stay balanced; I would fall over sideways, like the guy does in the second have of this "Goofus and Gallant" walking lunge video. But even after I could stay balanced, cranking out twenty reps per leg was and is very hard for me. Because of the weakness I have ... from avoiding lunges in the past.
When I step onstage again in July, I expect my vastus medialis muscles to be significantly improved over last year. Much of this improvement can be credited to the walking lunge.
It is the same thing in the spiritual life: Sometimes the particular kind of spiritual exercise we shun the most is the very thing that would benefit us most.