What you think and believe is manifest in your life.
Think negative thoughts, believe negative beliefs, and these will become manifest. On the other hand, develop a pattern of thinking that is positive and a deepening belief in abundance, and these thoughts and beliefs will be yours.
When writing your personal affirmations, always place them in present time.
"I am growing in abundance each and every day." is an affirmation that is in present time.
"I wish I could grow in abundance each and every day." is a wish — and sets your affirmation to come true at some point in the future.