Getting the Bow Drill technique down and understanding the various useable woods, pressures and speeds that it takes for success can be pretty tough. There are a lot of factors that can affect your outcome so I don't think I could help much without seeing your technique.

It could be something as simple as cutting a smaller notch in your hearth board or using a thinner board. A thick hearth and a large notch make for a lot of effort.

There are also external variables such as humidity and the dampness of wood to consider.

You should be able to get a coal with most Cedars, but they're not all the same. For example, it has been my experience that I can more easily produce a coal with Eastern White Cedar than I can with Eastern Red Cedar.

Willow and Basswood have always been easiest for me to use, though I've been told by some that it should be just as easy to use White Cedar.