I'm not sure who originally composed it, but it's written out as a personal outpouring to Hashem.
And while I intellectually know that it's essential to thank Hashem for the good as well as the bad, I sometimes find this difficult or agonizing if I'm going through a particularly painful time.
So reading this little card helps me out in those times when I don't have much heart to say the words on my own.
Also, because it's not a formal, institutionalized prayer, I believe you can feel free to say only parts of it, or just the first line or just the last line, or whatever you can manage. You can also add your own thoughts to it.
For example, there's a line that reads:
Creator of the World, I request forgiveness from the bottom of my heart if there were times I did not appreciate what You've given me and instead of saying "thank You," I only complained.
Well, speaking for myself, there's no IF. I definitely did not appreciate what Hashem was giving me and instead of saying thank You, I indeed complained and only complained. (Actually, it was more than complaining. It included tears of frustration & despair, caterwauling, accusations, and so on.) And it happened many times.
Just being honest.
So I can change that to read:
Borei Olam, I request forgiveness from the bottom of my heart for ALL the times I did not appreciate what You've given me and instead of saying "thank You," I only complained and in general responded with seething bitterness, resentment, rage, and self-pity.
The main thing is your heart and your honesty.
Also, I've translated the prayer into English. But personally, I prefer saying "koach" instead of "strength" and "Melech malchei hamelachim" instead of "King of kings of kings" (sounds weird in English, right?) and "Ribbono shel Olam" or "Adon Olam" instead of "Master of the World," and so on. So also feel free to mix in whatever languages best express yourself.
The main thing to keep in mind is this:
The happy fact about expressing gratitude to God is that ANY expression of gratitude, no matter how miniscule or half-hearted, is actually very powerful (even if we cannot perceive its effect).
A Prayer of Thanks to the Creator of the World
Thank you that I am standing here and thanking you.
And anything that I can possibly say to You is nothing in light of how much I truly need to thank You.
And so, I need to thank You for everything.
Thank You for everything in the universe.
Thank You for the many thousands of times You've helped me, supported me, saved me, rescued me, made me happy, healed me, protected me, encouraged me...
Thank You for always being with me.
Thank You for giving me the strength to fulfill mitzvot, the strength to do good deeds, and the strength to pray.
Thank You for all the times You helped me when I didn't know to say thank You.
Thank You for all the kindnesses You do for me each and every moment.
Thank You for each and every breath I take.
And thank You, Melech malchei hamelachim, also for all the things I don't have.
Thank You that it's hard for me at times.
Thank You for the times that are a bit sad for me too because everything is for my good. And even though I don't always see it as for my benefit, deep in my heart, I know that everything comes from You with grace and loving-kindness and tremendous compassion and it is the very best thing for me and is performed especially for me with precise and perfect hashgacha pratit (personal supervision), as only a Melech malchei hamelachim can do.
Thank You that it's sometimes difficult for me because only in that way can I know how to appreciate the good; only after we find ourselves in darkness is it possible to appreciate the light.
Thank You for the wonderful life You've given me.
Thank You for every miniscule thing I have because everything I have has been given to me by You, and not by anyone else.
Thank You for always listening to my prayers.
Creator of the World, I request forgiveness from the bottom of my heart if there were times I did not appreciate what You've given me and instead of saying "thank You," I only complained.
I am dust and ashes, and You are the entire universe.
Please, never distance Yourself from me.