Shepherd the Flock of God

So I exhort the elders among you, as a fellow elder and a witness of the sufferings of Christ, as well as a partaker in the glory that is going to be revealed: shepherd the flock of God that is among you, exercising oversight, not under compulsion, but willingly, as God would have you; not for shameful gain, but eagerly; not domineering over those in your charge, but being examples to the flock. And when the chief Shepherd appears, you will receive the unfading crown of glory. Likewise, you who are younger, be subject to the elders. What are elders to be aware of and act upon? Why is Peter addressing elders?