Main point summary
Respond to "life" with praise, confession and genuine prayer, for it is wonderfully powerful when the righteous actually use the tool of prayer.
Κακοπαθεῖ τις ἐν ὑμῖν,
Is anyone among you suffering?
Let him pray.
Is anyone cheerful?
Let him sing praise.
ἀσθενεῖ τις ἐν ὑμῖν,
Is anyone among you sick?
προσκαλεσάσθω τοὺς πρεσβυτέρους τῆς ἐκκλησίας
Let him call for the elders of the church,
καὶ προσευξάσθωσαν ἐπʼ αὐτὸν
and let them pray over him,
ἀλείψαντες [αὐτὸν] ἐλαίῳ ἐν τῷ ὀνόματι τοῦ κυρίου.
anointing him with oil in the name of the Lord.
καὶ ἡ εὐχὴ τῆς πίστεως σώσει τὸν κάμνοντα
And the prayer of faith will save the one who is sick,
καὶ ἐγερεῖ αὐτὸν ὁ κύριος•
and the Lord will raise him up.
κἂν ἁμαρτίας ᾖ πεποιηκώς,
And if he has committed sins,
he will be forgiven.
ἐξομολογεῖσθε οὖν ἀλλήλοις τὰς ἁμαρτίας
Therefore, confess your sins to one another
καὶ εὔχεσθε ὑπὲρ ἀλλήλων
and pray for one another,
that you may be healed.
Πολὺ ἰσχύει δέησις δικαίου ἐνεργουμένη.
The prayer of a righteous person has great power as it is working.
Ἠλίας ἄνθρωπος ἦν ὁμοιοπαθὴς ἡμῖν,
Elijah was a man with a nature like ours,
καὶ προσευχῇ προσηύξατο τοῦ μὴ βρέξαι,
and he prayed fervently that it might not rain,
καὶ οὐκ ἔβρεξεν ἐπὶ τῆς γῆς ἐνιαυτοὺς τρεῖς καὶ μῆνας ἕξ•
and for three years and six months it did not rain on the earth.
καὶ πάλιν προσηύξατο,
Then he prayed again,
καὶ ὁ οὐρανὸς ὑετὸν ἔδωκεν
and heaven gave rain,
καὶ ἡ γῆ ἐβλάστησεν τὸν καρπὸν αὐτῆς.
and the earth bore its fruit.
It only has great power if it is used! ("as it is working")
16d-18c is the Ground of all three scenarios/counsels, since (1) prayer is also the action point for the first scenarios, and (2) James does not provide an example inline with the scenario of the third.
Proverbial, normal result.