The definition of tireless is energized and enthusiastic, showing great energy or not easily fatigued.
If you are dedicated to helping the homeless and you spend countless hours continually fighting for their rights, this is an example of being a tireless advocate for the homeless.
- that does not become tired; untiring or unwavering
- characteristic of a tireless person; continuing, persistent, etc.: one's tireless efforts
Having or showing a capacity for persistent effort; not tiring or relenting: