Twenty-two affirmations for more energy — for the flat weeks when the tiredness is not really about sleep.

There is tiredness that sleep fixes and tiredness that it does not. The second kind is usually about how your days are arranged — too much obligation, too little that you actually want, no clear line between working and not.
These twenty-two affirmations aim at that kind. Several are about boundaries and where attention goes, because for most people that is where the energy is actually leaking.
Track it for a week rather than guessing. Most people find two or three specific things — a recurring meeting, a particular person, the last hour on the phone — that account for far more of their flatness than the schedule as a whole.
Then use the boundary lines rather than the vitality ones. "My boundaries protect my energy and well-being" is doing more real work here than any amount of visualised vibrance.

1. “I have an abundance of energy.”

2. “I am healthy and full of energy.”

3. “I invest time and energy into looking and feeling my best.”

4. “I have abundant energy, vitality, and health.”

5. “I send my body thoughts of energy and vitality.”

6. “I am attracting positive energy into my body.”

7. “I get out of bed full of energy.”

8. “I have abundant energy and vitality.”

9. “I let go of my worries. I focus my energy on only what I can control.”

10. “I am grateful for my good health and energy.”

11. “Setting boundaries helps me preserve my energy and well-being.”

12. “My body is filled with calm and peaceful energy.”

13. “My body vibrates with energy and health.”

14. “My body is healed, restored and filled with energy.”

15. “My body is full of energy and vitality.”

16. “My boundaries protect my energy and well-being.”

17. “My body is healthy and full of energy.”

18. “I focus my energy on my values.”

19. “I enjoy eating foods that give me lasting energy.”

20. “I have vibrant energy to enjoy my daily activities.”

21. “I appreciate the energy healthy food gives me.”

22. “I start the day full of energy.”
Not on their own. What they can do is redirect attention towards the things that drain you, which is where most fixable fatigue lives. If the tiredness is persistent and physical, that is a doctor's question, not an affirmation's.
Common causes are low activity, dehydration, stress, low mood, and days with no autonomy in them. Worth ruling out the medical ones — thyroid, iron, sleep apnoea — before assuming it is motivational.
The boundary and focus lines. Burnout responds to less, not to more enthusiasm, and affirmations about vibrancy can feel actively insulting in that state.
It can, if the gap is wide. Choose the lines that describe what you are doing — protecting energy, choosing where it goes — over the ones that describe a state you are not in.