Here's why:
* Gerunds are verb forms ending in "-ing" that function as nouns. They can be the subject, object, or complement of a sentence. In this case, "jogging" is the subject of the sentence.
* Participles are verb forms ending in "-ing" or "-ed" that function as adjectives. They describe nouns. "Jogging" isn't describing a noun in this sentence.
* Infinitives are verb forms preceded by "to" (e.g., "to jog"). This sentence doesn't have an infinitive.
Let me know if you have any other questions!