This depends on your shell. In case you use any of Bourne Shell derivatives (namely Bash) or Bourne Shell itself, put appropriate commands in ~/.profile
:
[ -z "$STY" ] && screen -Rd "work"
This will only start a screen session in case you're not already running inside a screen session (screen sets environment variable STY).
In case you're not using Bash or compatible, use the proper shell initialization file with a similar test.