There's
absolutely happiness after heroin addiction - take it from me!!

It is, after all, a matter of getting through the withdrawal stages - both physical and psychological (and spiritual, if you will). Sometimes, if your use has been especially problematic, you have PAWS (post-acute withdrawal syndrome) to contend with. This can last a while, so please be prepared for that. You can also be prepared, however, to come to know a happiness greater in recovery than you may have ever felt in active addiction. You will have known what it truly is to have been to hell and back; your happy days in sobriety will take on a whole new meaning now that you have come to know all-too well the monotonous drudgery of heroin addiction.
After plowing through the withdrawal comes the maintenance of your sober lifestyle stage. This is where most people get tripped up, because life isn't necessarily "easy" at first and, after all - why should it be easy? You've been getting quick fixes this whole time... so having to work for pleasure rubs against the very grain of people like ours' natures! This, however, is
normal. Bear that entirely in mind. It
does get better. We can, and do, get better if we try to maintain that precious something that is a sober lifestyle.
Are you interested in full recovery as in full sobriety? I might, in that case, point you towards our Sober Living forum (I could also move this thread there) if you're interested in more of a target audience for your questions... I do very highly recommend giving that forum a look-see regardless, by the way!
Thanks for your question...
All the best to you,
~ Vaya