According to

According to my opinion, we should go hiking. (Incorrect)

In my opinion, we should go hiking. (Correct)

"According to" is used with another person or source of information and is not used with 'opinion'. 

According to all these reasons, she decided to change jobs. (Incorrect)

For all these reasons, she decided to change jobs. (Correct)

"According to" is not used with "reason".