Depression comes and goes for me, most of my life. It was definitely there for the first 6 months or so after I quit smoking. I walked a lot. The emotions bubbled up like crazy, in waves, with sadness mixed the next minute with rage. Eventually, the pendulum slowed down, hitting the middle mostly. It feels like I will implode when strong emotions arise, but I haven't yet!
Hobbies. Get them. I enjoy walking, and I have turned into a jigsaw puzzle nut. I'm embarrassed to admit that, but I really enjoy it. lol! It just occurred to me; doing a puzzle is similar, in a way, to one of the parts of smoking I had trouble moving past, and that was what to do with my hands. I was a chain smoker, and so I was always "busy" with the habit.
I quit about five years ago now, and I have had a few weeks off and on of some depression, but avoided dipping into the suicidal ideology. I know that when those thoughts happen, It's time to call someone, either a friend or a professional, and get a bit of help until I come out of it.
Absent mindedness is a common symptom of withdrawal, by the way, along with, for some of us, a sort of grieving period for that really bad friend (smoking) that was totally bad for us but had been with us for a very long time. Stay close to the forum, Sammy. We'll listen.