I have been addicted to opiates twice in my life. Once was in high school with a standard high school whatever-pain-pill-i-can-get addiction. The next time was several years later with a much longer heroin-methadone-suboxone addiction. Both experiences were very similar to me, with the second being just like the first only exaggerated in every way.
WSB15 made a good list of points. I will try to line out my own things that helped me each time.
1. Be healthy. Exercise and eat well, stay outside for ridiculous amounts of time, sunshine.
2. Be social. Both times i quit i basically retired into myself afterward. This is incredibly counterproductive when you are trying to get your soul back. If you don't feel like you can be social you should do it anyway. It's like exercise, work but rewarding.
3. Be patient. Maybe the most important. If you don't feel yourself after a few weeks or months it is fine. You need to keep at it. If your interests are gone you need to keep trying. If you get a spark of interest or your old self, hold on to it. Know that recovery comes slowly and often in the night, meaning that you won't feel a switch coming on usually. It will be a gradual process that you might not notice at all. The thing is that you will eventually find yourself in a place where you can say, i am not back to where i was before my addiction, i am better than that and i am rewarded for it.
4. Be nzos. I would not exactly recommend these to anyone, but they have certainly helped me each time. Benzos help me with the lethargy and depression that lingers long after opiate addiction. I find they are most useful several months after quitting opiates on your own. I also find benzos very easy to quit, which is exactly the opposite of most people, so tread very carefully.
5. Be the future of yourself. There is no going back to who you were before, it is ridiculous to want that. You need to be happy with all of your life's decisions. You must understand you are only going to be the future and never the past, and the future will be better. I believe that relapsing is just an attempt to get yourself back into the past. Instead you must believe only in the future of you.
6. Be busy. Keep yourself interested in your life by finding something, anything that interests you and build up a hobby or project around it. Keep a small garden or some windowsill plants. Get some easy music production software and mess around with it. Buy some art supplies. Keep your production focused on the light inside of you, i find that trying to articulate my depression in any way just makes me more dark and depressed. Stay away from that trap. Work and work and you will be proud of yourself. It is that pride which becomes your new self, your new better self. Soon you will find that you have really lost nothing at all.