We use substances to help us deal with pain: emotional, relational, physical, etc. That means sobriety brings pain to the surface - the pain that we have been medicating away. But it is pain that prompts us to change. People don't come to see me when things are going great. People don't go to rehab because they have fifty thousand dollars to spend and eight months to kill.
So if we're newly sober and spending time with the same friends, a few things may become apparent:
How much they drink, smoke or use drugs.
What they are like when they do those things.
Maybe they are more enjoyable to be around when you aren't smoking, drinking or otherwise high - you can actually connect with them.
Maybe you find yourself the brunt of more jokes than you like.
Maybe, without the substances, you just don't have that much in common with them anymore.
Most of these experiences are unpleasant. The temptation can be to go back to drinking or using substances. Or we can let these unpleasant experiences prompt us to change. Change is scary and difficult but, without it, relapse becomes quite likely. We may have to ask ourselves - what kind of people do we really want as friends? Where will I find them? How can I befriend them?
Ultimately, the pursuit of sobriety and recovery becomes a question of identity. Anyone I have worked with who has done well, the conversation eventually turns to a question of identity: which means it is a good, if challenging, place to be.
Let the pain prompt you to change.