Manifestation requires a strong mind and affirmations are a great way of focusing your thoughts. Affirmations can either drive you to success or doom you to failure. Our parents probably taught the first affirmations, hopefully they were "Yes you can!" and not "That's impossible"
Our mind acts like a young child's when we hear affirmations, curiously the "not" is unheard so "You must not do that!" becomes "You must do that". And we wonder why kids play up.
First person and second pertson types of affirmation, the "I am wonderful" and the "You are wonderful".
The success of each depend on the individual. It may be down to whether we have a dominant or passive nature.
These are "I am" affirmations