It's like trying to add any new habit to your lifestyle, like doing more excercise or eathing healthy. It takes time and discipline.
You have to start at some point, but the important thing is to be constant on its practice. Start by creating test for lib or utility functions you create for your projects. Try to keep test simple, focus on inputs and outputs of your functions or methods, and avoid mocks, spies and stubs the more you can.
If you wanna know more I recommend these blog posts:
medium.com/@MarcFly1103/buckle-up-with-tape-1bd5e… medium.com/javascript-scene/what-every-unit-test-…