The word 'can't' is contraction for 'cannot.' Combined with 'help'
you are communicating something you are unable to control or
having a hard time gaining a grasp for. This can be a physical or
mental action.

"I can't help thinking about it."

"I can't help shopping so much."

"I can't help working all the time."

I can't help smiling when I see her."

"I can't help eating so much."

"I can't help loving you."

I can not help biting my nails when I am nervous."

"I can not help smoking when I have been drinking."

"I cannot help feeling so sad."

"I cannot help remembering the things you did."