I have noticed when learning English the word “it” is often left

out of the sentence. Many times this word is not really needed but in English it(😉) is used to make the sentence flow.

Example:
We are having a conversation about riding our bicycles.

“I like but is an activity that I have not performed in years”

Correct way:
“I like it but it is an activity that I have not performed in years”

“It” is used as a shortcut to reference the subject of the conversation without actually typing the subject each time.

These are acceptable forms of the sentence below, but I am showing examples to help your understanding of how to use “it”

“I like biking but biking is an activity that I have not performed in years”

You can replace the second “biking” with “it”

“I like biking but it is an activity that I have not performed in years”