Answer:
The sentence that distracts the reader from the main idea and should be removed from the paragraph is "That makes walking a simple activity for those new to exercise."
Step-by-step explanation:
The line "That makes walking a simple activity for those new to exercise." , adds information that is not necessary for the reader, since it is mention before and along the paragraph that walking is a simple exercise, then this line can be erased without affecting the message of the excerpt or the connection between the remaining sentences.