Testing private methods with JUnit [duplicate]

This question already has an answer here:

• How to test a class that has private methods, fields or inner classes? 37 answers

I'm getting into using Junit to test individual methods that have been implemented in a class. But it cannot test private methods. What is the best way to proceed? It seems like a bad idea to convert all methods to public and then back to private because the whole point of JUnit is to remove the chance of human error when manually testing.