Here are a few suggestions:
The Beatles - Let It Be
Bob Marley - Three Little Birds
Jason Mraz - I'm Yours
Ed Sheeran - Photograph
Adele - Someone Like You
John Legend - All of Me
Oasis
- Wonderwall
Louis Armstrong - What a Wonderful World
Bill Withers - Ain't No Sunshine
Elvis Presley - Can't Help Falling in Love
These songs usually have simple chords and melodies, making them suitable for relaxing and playing when tired. I hope this helps you enjoy the music and relax!