Why does a lizard become active in hot sunny weather during a cold snap become lethargic?

Lizards are reptiles that are cold-blooded organisms. This means that the body temperature of lizards is not constant, but directly depends on the conditions around the animal. This is due to the imperfection of metabolism and thermogenesis of lizards, whose heart is not divided into four full-fledged chambers necessary for full blood division. Therefore, the metabolism of lizards is highly dependent on the temperature of the environment. If it is tall, the lizard becomes active, because its metabolism is accelerated. In cold weather, the metabolism is slower and the lizard calms down.