“…but to think soberly, according as God hath dealt to every man the measure of faith.”
Romans‬ ‭12‬:‭3‬

The Bible says:
“So then faith cometh by hearing, and hearing by the word of God.” Romans‬ ‭10‬:‭17‬
So if you think you might be experiencing doubts about any subject matter or worse still, you seem to have taken up different fears- fears of a better future, fears of a better job, even fears of your eternal destiny, there is an effective way to handle that- cause faith to come to you.
The antidote to doubts and fears is faith, and you can cause faith to come to you, you have been dealt the measure of faith, a definite amount, but you can cause more faith can come to you.
If you are experiencing doubt in a particular subject matter, simply plan to spend more time hearing God’s word around that subject matter.
If God can take a shepherd boy from the bush or a man who was imprisoned falsely and make them rulers; then with him, there should be no fear concerning your future.