If a plant looks dull and keeps showing signs of stress, place it outside in a bright, shaded area, somewhere with indirect sunlight.
If a plant has successfully endured all seasons and remains healthy, it means it's really settled in and happy. You can place it outdoors and even propagate new plants from it.
Plants don't like being moved around or having their pots changed too often. Try to find a good spot for them and let them be.
Avoid tilling the soil or loosen the soil in your plant's pot. Just let it be unless you have a very specific reason to check the roots.
Always choose plants that suit the size and layout of your space. A huge plant in a compact area will make it hard to move around and can stress out the plant too.