9. Resolved, To think much, on all occasions, of my own dying, and of the common circumstances which attend death
Anyone reading at that most likely is thinking: "what?". It seems too harsh for anyone to trouble himself with such a burdensome thought. Doesn't this contradict our former resolution of "living to the full"?
One should go here with the author's intent. Why would he think it profitable to himself to entertain thoughts of his own dying? Which common circumstances of death was we referring to? Would occupying his mind on this would render glory to God?
Honestly, I don't see it clearly. But I have some observations:
1. He is not saying he will entertain thoughts of other people dying.
I find it hard to believe for Jonathan Edwards to sit and watch horror movies on a t.v. screen -I don't like them either!
2. It brings no comfort at all for an unbeliever to think of his own dying.
It is terrible for an unbeliever to entertain thoughts of his own dying. It could make him sad. It might plunge him into depression. Tears may even be shed while thinking of circumstances of his own dying. But not necessarily because of missing himself on earth. Those bitter tears might even come at imagining his own dying as a late vindication before people who unyieldingly defied every capricious act of his.
3. Properly done, thinking of his own dying could comfort the one who trusts Jesus.
I can see a bad way to entertain thoughts of your own dying: to think about it in the same way an unbeliever does. Maybe like what was described above? OK, but if you are to think properly about it, how are you to see your own death? Should it bring joy to your heart?
No and yes. First, I say no, because real sadness may surely befall you when thinking about what would happen to our relatives and friends after we're gone from this world. You would comfort yourself by praying and believing that God will take care of them. Last but not least, I'd say YES, because once you die our mission is over. You're finally meeting Jesus! Wasn't that what you always wanted? Wasn't that your best dream ever while alive on earth?
May it be so.
32 And what more shall I say? For time would fail me to tell of Gideon, Barak, Samson, Jephthah, of David and Samuel and the prophets— 33 who through faith conquered kingdoms, enforced justice, obtained promises, stopped the mouths of lions, 34 quenched the power of fire, escaped the edge of the sword, were made strong out of weakness, became mighty in war, put foreign armies to flight. 35 Women received back their dead by resurrection. Some were tortured, refusing to accept release, so that they might rise again to a better life. 36 Others suffered mocking and flogging, and even chains and imprisonment. 37 They were stoned, they were sawn in two,  they were killed with the sword. They went about in skins of sheep and goats, destitute, afflicted, mistreated— 38 of whom the world was not worthy—wandering about in deserts and mountains, and in dens and caves of the earth. (Hebrews 11:32-38, emphasis mine)
In Christ, we will surely rise to a better life.