Our environment has an effect on how we feel. I notice that an untidy room makes me feel bad about myself (and feeling bad about myself leads me to think that spending time tidying my room is time wasted — after all I’m not that important).
If you want to change how you feel you can alter your environment. If you’re in an emotional rut you can do something as simple as take a new route to work. Or you can clear up (you can clear up my room too, if you want!).
Or you can take a walk in the park, or in the woods, or take a hike in the hills, or take a different route to work. Park further away and make time for a walk. Take your lunch somewhere new. All these little things can help to shift a settled mood.
When you meditate, you can make your environment supportive of your efforts to develop Metta by creating a beautiful space to meditate in. You can make a shrine that expresses your ideals. Candles, incense, flowers, and images that are meaningful for you can all help to uplift your emotions.
You don’t have to use Buddhist images of course. You can use images from nature, or pictures of figures that inspire you.