I've done the Landmark Forum and it was great. It undid all the years of JW brainwashing and gave me a whole new fresh perspective at life.
Like they tell you at the start of the forum, "None of it is true".
It's just a series of discussions and realizations that help equip you with techniques that allow you to remove a lot of the mental blocks that prevent you from reaching and defining new goals.
I definitely recomend it.