Answer:
1) "Jogging is more than exercise"
2) The second paragraph is explaining the second reason to why jogging is more than exercise
3)
"Jogging causes the body to produce a group of hormones called endorphins" (shows how jogging can help with arthritis, etc.)
"A bonus can be increased self-esteem through weight loss and better body image" (shows how jogging can increase confidence)
"Sustained running also requires self-discipline, which can benefit a runner's ability to stay with a task to completion." (shows how jogging can increase confidence)
Explanation:
for number 1:
"Jogging is more than exercise" is the writer's claim because usually the first sentence of the paragraph explains what they think, and the rest is why they think what they think (evidence and explanation of evidence).
for number 2:
The paragraphs to explain the writer's reasoning behind their claim in general, so naturally the second paragraph is just that, the second reasoning behind why the writer thinks jogging is more than exercise.
for number 3:
Evidence and explanation of evidence is what makes up the middle of every body paragraph in essays, so it's just a matter of seeing which sentences are the evidence and which are the explanations of evidence. I'm not sure about the third evidence I put, but I think it's right.