Identifying Author's Tone in a Journal Entry

Read the following excerpt from a fictional journal entry:

"I strolled through the park today, watching children laugh and play while the sun painted the sky in vibrant hues of orange and purple. It was one of those rare moments that felt like time itself had paused, allowing me to truly appreciate the beauty around me. However, beneath the joyous exterior, I sensed an undercurrent of change, as if nature was whispering secrets of transformations yet to come. I couldn't help but feel a mix of gratitude for the present and apprehension for the future."

Based on the author's writing style in this excerpt, what is the tone of the piece?