My team and I get asked questions all the time about the quickest three things to do for this or that or all of the above. Building a healthy culture and an authentic Positive Energy Workplace™ takes awareness, honesty, intention, energy, presence, and action. It doesn't have to take a ton of time, however, you want to watch out for "doing" those quick three things just to the "check cultural health" box off your list.
If you are truly tending to your IEP (Intentions/ Energy/ Presence) and taking action from a place of awareness and service... you won't need a quick checklist, your culture will take care of itself. That said, if you do want some quick things to start paying extra attention to, I've shared some in the below video (timestamp below post).