Since marijuana is both a depressant and a stimulant, smoking cannabis can have mixed outcomes for people using marijuana to cope with stress or anxiety.
Feeling anxious can make it hard to enjoy life, and it's not easy to just "fix" being overtaken by a racing reel of negative thoughts by keeping a gratitude journal, or taking deep, cleansing breaths, or whatever else it is your non-anxious friends say helps them deal with their worries.