Is it wrong to smoke marijuana before work?

I am nearly 50 years old and I have been an everyday marijuana smoker for most of my life. I suffer greatly from depression and the marijuana seems to be the only non-prescribed thing that works for me. I have never had great jobs and don’t make enough money for insurance. This leaves me in a bad situation when it comes to work. I either go depressed and deal with the depression and anxiety all day or I self medicate and use marijuana before work…To be honest I smoke everyday before work and nearly everyday while I am on my break…I of course have to sneak to do it and I am just barely escaping being caught more and more. I feel a bit guilty and feel like I am doing wrong but I also feel like I have no choice…What do you think? Is it wrong to smoke Marijuana at work?