Others may just appear to look unhealthy for no apparent reason. I don't believe that they understand you, but plants breathe CO2 which we exhale, and in turn they exhale oxygen which we need. I've heard of oxygen bars where you PAY to breathe canned oxygen. Seems to me to be more prudent to have a chat with your Philodendron, and give each other a boost. I suppose that the most important elements needed for plant health are water and light.
Most plants have dormant and active cycles.
Watering, just as feeding your plant differs greatly from season to season. Plants sense the natural shortening of daylight hours and may go dormant as they would in their natural habitat. This is usually a time when the amount of watering is decreased. On the other hand, many plants actively begin to grow or bloom, so they must have more water, and be fed. While plants are dormant they should only a minimum amount of water each time that the soil becomes dry to the touch an inch below the surface.