Marlynn,
To keep your bread supple, first and foremost knead as LITTLE flour
into it as you possibly can and still work with the dough. It's all
to easy to continue to add flour while kneading; in the end, it soaks
up too much of the liquid.
Second, consider starting with a "sponge" -- basically, you mix all
the liquid but only about half the flour. Especially useful if
you're using whole grains. You need it to be stiff enough to rise in
the bowl, but far from knead-able. Think a little looser than muffin
batter. Give it the traditional 120 strokes with a strong whisk or
wooden spoon -- you'll see the gluten start to develop and the batter
smooth out as you work. Let the first rise happen in your mixing
bowl, allowing the grain to absorb as much liquid as it wants. (Try
to put all the coarsest ingredients -- not only whole-wheat flour,
but rolled or steel-cut oats, wheat berries, barley flakes, etc. --
into this first rise-and-hydration step.)
After that first rise, you can add your salt & oil (or other
fat). For best-keeping bread, keep your oil on the high side of the
amount recommended in the recipe. With those components well-mixed
into the sponge, add the remaining flour (just enough to be
knead-able!) and knead to make the smooth, supple dough you can
shape. With that first rise having helped develop the gluten, you
may find you don't need to knead quite as long, a nice side effect.
Using the sponge to hydrate the coarser ingredients, and then working
as little flour as possible into the kneaded dough, I hope you'll
find your bread is closer to your goal!