lighthearted
adj.adj. having a cheerful and friendly attitude. You use this to describe someone who is not serious or someone who makes others feel relaxed.
adj. characterised by a cheerful, friendly, and easygoing nature. Often used to describe a person's disposition or the tone of a conversation.
He has a lighthearted way of looking at life.
The meeting started with a lighthearted game to help everyone relax before discussing the serious budget issues.
Despite the gravity of the situation, the manager maintained a lighthearted tone to prevent the team from becoming overly anxious about the upcoming merger.
From Middle English lyght hertyd, liȝt-hertid, from light (adjective) + herted, hertid (“having a disposition”, adjective) (equivalent to light + hearted), from the noun herte. See more at light, heart, -ed.