Antonyms for the word "low-spirited" include "cheerful", "optimistic", "happy", "joyful", "vibrant", and "upbeat". These words convey a sense of happiness, positivity, and energy, which are the opposite of feeling low-spirited. A person who is cheerful is likely to be in a good mood and display a positive attitude towards life. Being optimistic indicates that one has a hopeful and positive outlook, even in challenging situations. Being happy and joyful implies a sense of contentment and satisfaction with life. Vibrant and upbeat suggest energy and enthusiasm, which can elevate a person's spirits and help them feel more alive.