I set an alarm for when I'm supposed to stop work, close everything and then set it out of sight (my laptop goes in the closet). I find the Pavlovian conditioning helps stop my mind from ruminating after a certain time of day.
I would like to point out that within this comment you argue quite correctly that averages of groups should not be extrapolated to the entire group. However in most of your argument you propose that companies and societies will extrapolate IQ research to the group and discriminate on those bases.
Now I'm not saying anything about your personal views about the research, but I think in order to fix the cultural and societal discrimination you touch upon we should emphasize exactly the reasoning you expounded about the nuance of averages. We know that there is more differences within groups than between them and I think to deter the effects of discrimination we need to emphasize analysis on the individual level and to have a real and honest discussion about the issues and to make statistical reasoning more prevalent among the general population.
I've also similarly made many friends through playing Tekken offline. I believe the local aspect of fighting games (as opposed to most online games nowadays), and the depth of its mechanics is very conducive to making a wide variety of close friends (old and young). I recommend people check out fighting games or games that require person to person contact to make more friends.