If you are using the Windows key (Mod4) as modifier in i3 because some application has keyboard shortcuts with Alt but don’t want to sprain your thumb every time you switch to another workspace (is this how normal people press the Win key?) there are two easy fixes:

Swap the Left Alt and Windows Keys

setxkbmap -option altwin:swap_lalt_lwin


Remap Print to the Winows Key

This way you can strain your right thumb, too!

xmodmap -e "keycode 107 = Super_L"


Both changes are only temporary, to excute them each time X11 is started add both commands to .xinitrc.