Your heart rate will go down, causing you to cool down before you are done exercising. This is good because then you won’t have a high heart rate for a long time.
There are obviously A LOT of them. Like how your brain is slowly deteriorating, which is scary and dangerous. I can't cover everything but I have a website link you could visit that talks about this subject
https://www.drugabuse.gov/publications/research-reports/heroin/what-are-long-term-effects-heroin-use