About to start BCS for the first time but i had a question first

It's been a LONG time since I watched Breaking Bad. and I was wondering why Saul is hiding away and sad at the beginning of the first episode. I was gonna look it up, but I was worried about spoilers. I'm assuming it's because of what happened in Breaking Bad, since he's watching the old commercials of himself n' stuff, but for the life of me I can't remember if something BIG happened to Saul or if I'm supposed be confused as to why he seems so sad