Well, there are many ways to skin a cat...er, teach retrieving.
I prefer a motivational method for teaching the exercise, but I do use a correction for not retrieving once the dog understands the exercise. For Ilsa, I think she's needed a correction all of twice in her entire retrieving career because she lives for the dumbell.
I initially teach the dog to "take it" by holding a treat behind the db bar. When the opens its mouth to go towards the treat, pop the db in her mouth and gently hold her mouth closed for a second by holding up the chin. Then give them an "out" command and gently take the db and give the treat. You then build up the amount of time she holds the db.
I think it's important not to skip steps, I like to have a really solid "take it", "hold", and "out" before I add movement. In the meantime, you can continue to build db drive by teasing her with it when you are not actively training.