The first thing I gave up last year was my eating disorder. January 29th, 2021 was the last day I engaged in it. February 16th, 2020 was the last day I self-harmed. Smoking was probably the hardest for me, and I didn't start the quit until about March. It was the hardest to cope with the cravings.
I will say this. I don't think I could have quit any of those things without the support I got from others. It isn't easy to admit that you have an addiction to others, but having people you can talk to makes a big difference.
I haven't ever given up something as extreme as meth or heroine/opiods, but the people I've met who have got through it with a strong support system. Support goes a long way.