This is the 152nd most frequent Spanish word.
aunque
"Although" or "even though."
Here, 'aunque' is used to introduce a contrast or concession between being tired and still deciding to go to the gym.
Aunque estaba cansado, fue al gimnasio.
Although he was tired, he went to the gym.
Here, 'aunque' is used to express disbelief or an impression contrary to what might be expected.
Aunque no lo creas, ella completó el maratón en tres horas.
Believe it or not, she finished the marathon in three hours.
In this sentence, 'aunque' is employed to highlight the unexpected action of going to the beach despite the rain.