Like with everything in life, you can only develop if you take the first step. And that is applicable to almost every situation you may encounter:
Quitting a job is hard and takes courage, but may well be worth it if the next one has the potential to give you more joy in life or lets you have experience in a new field of work.
Learning something new always takes time and effort, but it may provide useful down the road, wether it’s profesionally or in your personal life.
Bottom line is, working hard and developing yourself is not comfortable as it requires you to step out of your current comfort zone and exposes your to temporary discomfort, but is neccessary to be comfortable and more happier later.