I tried it and had experiences even when I had blasphemy doubts ! I tried it more than one time and it worked like a miracle, all you need is little faith and little concentration.
Relax and have little disturbance (like any prayer as meditation is the prayer originally so you connect deeply with god) and have your rosary in your hand (optional of course) and repeat a lot of times "Forgive me God, Forgive me God ..... etc" keep repeating it like thousands of times if it is available.
what are the benefits so?
Quran said it and they are the same literally
(And said, 'Ask forgiveness of your Lord. Indeed, He is ever a Perpetual Forgiver.
He will send [rain from] the sky upon you in [continuing] showers
And give you increase in wealth and children and provide for you gardens and provide for you rivers.) Nuh 10-12.
(And O my people, ask forgiveness of your Lord and then repent to Him. He will send [rain from] the sky upon you in showers and increase you in strength [added] to your strength. And do not turn away, [being] criminals.") Hud 52.
(But Allah would not punish them while you, [O Muhammad], are among them, and Allah would not punish them while they seek forgiveness.) Al-'Anfāl 33.
It really made me more strength physically and had twice 50 pounds from the bank and the rain came.
Ok I am a liar, try it yourself and prove it to me
Also Allah in the bible said
(If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.) John 1:9.
(No, I tell you; but unless you repent, you will all likewise perish.) Luke 13:3
All regards <3