Answer:
The subject of the sentence is "I".
Step-by-step explanation:
The subject of a sentence can be defined as the sentence's topic, that is, what the sentence is about, or the person, object, animal etc. that is performing the action expressed by the verb. The subject establishes a relationship with the verb represented by its conjugation.
In the sentence "Every morning, I like to stop at Starbucks on my way to work," we can ask a simple question to the verb to find its subject. Who likes to stop at Starbucks? I do. "I" like to stop at Starbucks, therefore, "I" "am" the subject of the sentence.