Invitation is a good word, because it admits gratitude might not come. You can't force the feeling; you can only set conditions and wait.
Those conditions are mostly about pace. Gratitude rarely arrives at full speed — it needs a gap. Which is why it turns up in showers, on walks, in the ten minutes before sleep, and almost never during a scroll.
If you've been trying to feel thankful and getting nothing back, you may not need more effort. You may need a slower five minutes.
Leave a gap somewhere today and see what walks in.