Improve lighting.
Lighting plays a crucial role in workplace wellbeing; from an office refurbishment perspective, having and using as much natural light as possible is recommended, so window displays are important. It's also important to have a strategy for areas that are designed for distinct types of work too; artificial lighting, such as LED, can create a limitless spectrum of colour meaning that no one environment will have the same, constant shade of light thrown down upon it.
Think about colour.
Colour, like the lighting, has a major impact on the mood in the office, with certain colours helping to set a sense of calm or driving creativity. This is why office designers aren't afraid of embracing colour in workplace wellbeing; more brighter colours, usually associated with home interiors, have been making their way into offices. This helps to create a 'home from home' in the workplace; the thinking being that we feel comfortable, safe and content at home, so using similar colours to create the same feelings in the office will help to boost the mood during the working day.
Bringing nature indoors.
As humans, we are drawn to nature and the concept of Biophilic Office Design takes advantage of this; using lighting, colours and natural materials. Aside from the aforementioned natural light and colours, introducing greenery (such as plants and living walls), improving the views from key working spaces and incorporating natural finishes (such as wooden or reconstituted wood tables and finishes) are great ways to create a Biophilic effect within the workplace.