Affirmation and Meditation Question

I have this amazing app with positive affirmations from Louis Hay that I love. I find it very helpful and soothing.

Here is the problem: the affirmation is :
I feel healthy and alive.
The food I eat contributes to my vibrant health
I feel vibrantly healthy and alive

The truth is that I feel tired, lethargic and fat.
I can say “I am vibrant, I am healthy and I am alive” and believe it because its the truth but saying the affirmation is a lie to me.

What is Brookes thought about affirmations?
And what can I do to feel healthy and alive instead of lethargic and fat.