Lizards are cold blooded meaning they cannot regulate there own body heat. In order to maintain a livable body heat they need to sun and cool themselves through out the day. This is their way of maintaining homeostasis or an equilibrium in their bodies.
By the way this should be under science not English.
Answer: I think it means, the person who wrote the song wishes that they could be enough for a loved one or a friend, but can't provide that friend or family's needs, so they will still be with them, and provide what they can to the person.
