I wanted to ask how a person can control or even stop the satanic thoughts? For me when I am sitting and thinking the shaytan comes around and says things to make me disbelieve. How do I strengthen my heart in order where the shaytan can come and whisper. It’s like I’m in a spiritual pause

It was narrated on the authority of Abdullah bin Sinan that he said: A man complained to Imam Sadiq (peace be upon him) of excessive desire and whispering.
He said: “Command your hand over your chest, then say: In the name of God, and by God, Muhammad is the Messenger of God, and there is no might or power except with God, the Most High, the Great. times, God Almighty will wipe away from you and distract.”

As narrated, you need to repeat this all the time:
Put your hand on your cheat then say:
بسم الله و بالله محمد رسول الله ، و لا حول و لا قوة إلا بالله العلي العظيم ، اللهم امسح عني ما أحذر ، ثم أمر يدك على بطنك و قل ـ أي كرر الدعاء السابق ـ ثلاث مرات ، فإن الله تعالى يمسح عنك و يصرف " .