Here is a practice that will change what you believe about prayer within a year, and it costs nothing but a notebook.
Write down what you ask and the date, and leave room for the answer. Memory keeps the unanswered prayers and quietly discards the answered ones.
Write down what you ask for, and the date. Leave room on the right. When something happens, write that down too, with its date.
That is the entire system.
The reason it matters is that human memory is badly designed for this. We remember the prayers that went unanswered with painful clarity and forget the answered ones almost immediately. Something we begged for in February is simply the way things are by September. The relief gets absorbed into normal life and never gets counted.
A written record refuses to let that happen. It makes gratitude specific and it makes faith evidential. When you are in a hard stretch and God feels distant, you can turn back four pages and read, in your own handwriting, a thing you were desperate about that is now resolved.
A few notes on doing it well.
Keep entries short. One line. Elaborate systems die.
Write the honest request, not the tidied one. If what you actually wanted was for a situation to just end, write that. Future you needs the truth to compare against.
Record the no answers and the different answers too. Some of the most important entries are the ones where God did something other than what you asked, and you can now see why.
Psalm 77 shows the psalmist deliberately remembering the works of the Lord in a season when he could not feel them. Remembering was a discipline, not a mood.
Give yourself something to remember with.