Happy-go-lucky:
describes someone who is cheerful and carefree, not worrying much about problems or what might happen in the future.

Example:
1- Despite the difficulties of leading a country during the war, Winston Churchill often showed a carefree attitude in private, making jokes to cheer up the people around him.

2- When her homemade cake fell apart before the party, Sarah’s cheerful attitude turned it into a “cake decorating contest” where guests could help fix it.