I have trouble with naps. The only way I manage to take one every now and then is sometimes when I come home from work and happen to lay down on the bed, maybe play with the dog or whatever, then start to feel tired. But, I can't just decide to "lay down and take a nap because I always get that feeling that I should be doing something productive (believe me, I know naps are productive too!).

I just can't seem to relax enough, which is probably why I have so much trouble LDing in the first place. I have a really comfortable airbed and sometimes that's all it takes for me to lay down and take a break - but it doesn't often turn into a nap.