I got some embers by using a thin, well seasoned hazelwand on a hazel hearthboard. I used a very long drill (when kneeling, the top of the drill was at the same height of my head). This enabled me to get a lot of spins before I had to start of from the top again.
What you say about stamina is very true. When I was learning the bowdrill, I laid the set out in the garage. Every single time I needed something in the garage, I gave it a try. All these little moments of practice (only takes 2 minutes at a time) build up muscle memory and stamina very fast. I did exactly the same with the hand-drill, with good results.