As you say if you did Aikido in the early days you needed stamina, lots of energy , determination and an ability to endure pain.Misogi training was serious stuff.3000 Suburi off the belt, hundreds of suwariwaza ikkyo non stop.Your gi would be soaking , like a washing cloth.Despite the fact I had years of Judo training under my belt, aikido was sure tough.After a few sessions under Chiba Sensei my body ached from top to bottom.I think the Judo was a necessary process in order for me to enter the Aikido community. I am indebted to all my Judo teachers and erstwhile training partners for their efforts in forging my body and my mind. Oh , how I miss the good old days!!
I have yet to train or meet with Chiba sensei, but I do love hearing stories from my sensei. Sensei was giving us a short lecture the other day (that Chiba had given at a seminar a while ago) about not turning our hips when he wants us to and turning them when he doesn't want us to.