@thor

Engaging in open-source projects or Wikipedia is quite rewarding in terms of sense of life and self-esteem. It gives you occasional adrenaline rush when fighting idiots, which you inevitably meet on your path. Generally escape into nerdiness works, as it leaves you no time for existential worries :)

You should also follow @dump_stack advice and visit St Petersburg. Or Transsiberian Railway. Travel and change of scene is good too.