Here’s one of my favorite brain teasers… it may sound weird but this exercise requires a lot of thought.
You’re going to start with your feet shoulder width apart and two dumbbells by your side and your palms facing each other. Raise one dumbbell straight out to the side and the other in front of you. Your aiming to get both arms parallel to the ground and then back to the starting position and then alternate the other side.
This is a great exercise for the deltoids (shoulders) and also your core. If you want to add another challenge do this while standing on a bosu ball.