Yes to everything Sherrie said (well, except that I actually like the 100% whole wheat bread a lot) 
Whole wheat, specifically the bran particles, cut the gluten strands that make up a bread’s structure. Without enough structure, the bread is dense, not light. So to compensate, you add more gluten, either by combining the whole wheat with a high gluten flour or by adding vital wheat gluten.
And just to reinforce Sherrie’s tips, the other things you can do are to add a touch of oil, to soak the whole wheat flour with some of the water and salt from the recipe overnight, to limit rises to 1.5x, and to use a fairly well hydrated dough.