Routine
Make it routine to ask how people are. The important thing is to make talking about how people are feeling and coping, normal.
Taking regular opportunities to check-in on mental health and stress levels helps make conversations feel less out of the blue, intimidating or like another pressure for the ever-growing to-do list.
Taking regular small steps often makes a huge difference. These conversations can fit into an existing one-to-one, they could be built into the next training day or a new catch-up could be set up solely to talk about stress and how to prevent it.
There is no strict format for these conversations, the most important thing is that employers make time available for line managers and employees to have these open and honest conversations.