I've noticed one thing: You tend to not dream about things that stress you out. Many times you'll find yourself dreaming about relaxing situations. Even action packed dreams count towards this, and they tend to be enjoyable at their roots. Personally, I use passive awareness. I won't be focusing on being 100% aware 24/7, but I will be on the look out for ANYTHING odd or out of the usual. I switch back to active whenever something odd does happen. Passive is too keep me on the lookout, while active is activated right after I notice the odd happening. I even created a technique for this: CSSA. I believe you may have come across it a while back Brite.
In the beginning, I feel that all awareness is mentally exhausting. However, once you've been with the technique for around 2 weeks or a month, it starts to become a part of you as long as the act of mindfulness itself is not stressful. Some may be able to adjust quicker, others adapt slower.