english grammar..

It is better to rewrite it as following.

Don't regret because it is chosen by yourself.

or

Don't regret as it is chosen by yourself

or

Don't regret as this way is chosen by yourself.

or

Don't regret as this is your own choice. = This is the best and most simple.

This sentence is grammatically correct, but if I were you, I would change the sentence in the following way:
Don't let "yourself" regret, because "this" way is chosen by "yourself".