It depends on what time. I feed between 5-7pm. So if we are going to agility/ob class, it's an empty stomach. If we go up to the school for off leash play/training, it's usually after he's eaten (I wait at least an hour before any hard exertion). I don't use treats in training, only toys. I use a tug at agility/ob class, and a ball or frisbee at home.
For attention, it's strange. When we are at class, he's right on me the entire time- like he knows it's time to work. When we are at the school, since our training is based on him getting his frisbee or ball, his attention is on me. At home when we do stuff, I will make a click sound to get his attention. He loves to play ball, so unless I want to throw the ball hundreds of times while I'm sitting in my chair, I will make him do a long, long down/stay before I release him for the ball- 15-20 minutes at times. I don't expect him to keep his eyes on me that entire time, so I'll click to get his attention, then release him to go get the ball.