Someone who is lighthearted is cheerful and happy.
I was amazingly lighthearted and peaceful.
我当时出奇地轻松和平静。
Something that is lighthearted is intended to be entertaining or amusing, and not at all serious.
There have been many attempts, both lighthearted and serious, to locate the Loch Ness Monster.
为寻找“尼斯湖水怪”,已经进行了很多或轻松有趣或认真的尝试。