I have been planning to cast a spell tonight on the full moon for the past month but I have happened to fall ill and do not have the energy. Is there anyway I can still cast a spell in a way which would be easier for me or shall I leave it till I am back to full health.
You can always adapt your spells and workings to fit your needs. You can channel energy from many sources instead of drawing on your own energy. It really depends on your needs and prefrence, and of course what your intent is and the method in which you choose.
If you don't feel up to it then I recommend doing your spell when you feel well enough to do so. Just do what your comfortable with.