Exercise thyself to godliness [1] After having instructed him as to doctrine, what it ought to be, he now also admonishes him what kind of example he ought to give to others. He says, that he ought to be employed in "godliness;" for, when he says, Exercise thyself, he means that this is his proper occupation, his labor, his chief care. As if he had said, "There is no reason why you should weary yourself to no purpose about other matters; you will do that which is of the highest importance, if you devote yourself, with all your zeal, and with all your ability, to godliness alone." By the word godliness, he means the spiritual worship of God which consists in purity of conscience; which is still more evident from what follows, when it is contrasted with bodily exercise.

Footnotes

1 - "He who wishes to be faithfully employed in the service of God must not only avoid, as Paul says, the lies and superstitions that tend to poison souls; but he must avoid profane fables, that is, subtleties that cannot edify, and that contain no instruction which is good for the salvation of souls. Here is a passage that well deserves to be considered; for we see that it was a part of the corruptions which came into the world, and which, even at the present day, prevail in Popery. True, there will be doctrines in the highest degree absurd, and errors most foolish and debasing. We know that idolatry is as gross and flagrant among them as it ever was among the heathens, that the whole worship of God is corrupted, and, in short, that there is nothing which is not spurious. Such errors ought to be held in abhorrence by us; but there is an evil which is still more concealed, and which is unknown to the common people. For although the doctrine of the Papists were not false as it really is, though it were not perverse; yet it is "profane," as Paul calls it here. And why? They have questions which they debate, about things in which there is no profit. Were a man to know all the questions that are debated in the schools of theology of Popery, there would be nothing but wind. Yet they give themselves the greatest trouble about these matters, and can never succeed; for they put forward questions that cannot be answered but by divination; and though a man should wish to search out the secrets of God, about which nothing is said in the Holy Scripture, does he not plunge into an abyss? Now the Papists have had that pride and audacity, to wish to inquire into those matters which ought to be unknown to us. And thus it was that God withdrew his truth, when the world so corrupted it." -- Fr. Ser.

But refuse - That is, refuse to pay attention to them, or reject them. Do not consider them of sufficient importance to occupy your time.
Profane - The word here used does not mean that the fables here referred to were blasphemous or impious in their character, but that they had not the character of true religion; 2-Timothy 2:16.And old wives' - Old women's stories; or such as old women held to be important. The word is used here, as it is often with us, in the sense of silly.
Fables - Fictions, or stories that were not founded on fact. The pagan religion abounded with fictions of this kind, and the Jewish teachers were also remarkable for the number of such fables which they had introduced into their system. It is probable that the apostle referred here particularly to the Jewish fables, and the counsel which he gives to Timothy is, to have nothing to do with them.
And exercise thyself rather unto godliness - Rather than attempt to understand those fables. Do not occupy your time and attention with them, but rather cultivate piety, and seek to become more holy.

But refuse profane and old wives' fables - This seems to refer particularly to the Jews, whose Talmudical writings are stuffed with the most ridiculous and profane fables that ever disgraced the human intellect. It may with equal propriety be applied to the legends of the Romish Church. Let any man read the Aurea Legenda, and he will find of profane and old wives' fables what may stand, with considerable propriety, column for column with the Talmud. See Joseline's Life of St. Patrick for miracles, without rhyme or reason, abundantly more numerous and more stupendous than all the necessary ones wrought by Jesus Christ and his apostles. This is enough to persuade a man that the Spirit of God had these very corruptions and this corrupt Church particularly in view.
Exercise thyself rather unto godliness - To understand this expression it is necessary to know that the apostle alludes here to the gymnastic exercises among the Greeks, which were intended as a preparation for, their contests at the public games. They did this in order to obtain a corruptible or fading crown, i. e, a chaplet of leaves, which was the reward of those who conquered in those games; Timothy was to exercise himself unto godliness, that he might be prepared for the kingdom of heaven, and there receive a crown that fadeth not away. See the notes on 1-Corinthians 9:24, etc.

(10) But refuse profane and old wives' fables, (11) and exercise thyself [rather] unto (g) godliness.
(10) He contrasts again true doctrine not only with the false and apostate doctrine, but also with all vain and curious wiles.
(11) It is not only necessary that the minister of the word be sound in doctrine, but also that his life is godly and religious.
(g) In the true serving of God.

But refuse profane and old wives' fables,.... Either Jewish ones, the traditions of the elders; or those of the Gnostics, concerning God, angels, and the creation of the world; or those doctrines of demons, and which forbad marriage, and commanded abstinence from meats before mentioned; which are called profane, because impious and ungodly, and old wives' fables, because foolish and impertinent; and which were to be rejected with abhorrence and contempt, in comparison of the words of faith and good doctrine.
And exercise thyself rather unto godliness; either to the doctrines which are according to godliness, and tend to godly edification, which the above fables did not, study these, meditate on them, digest them, and deliver them to others; or to a godly life and conversation, exercise thyself, to have a conscience void of offence to God and men; or to internal religion, inward godliness, the exercise of the graces of faith, hope, love, fear, reverence, humility, &c. or rather to the spiritual worship of God, according to his will, not in a formal, cold, and customary way, but with the heart, in truth and sincerity, in faith, and with fervency and purity.

refuse--reject, avoid, have nothing to do with (2-Timothy 2:23; Titus 3:10).
old wives' fables--anile myths (1-Timothy 1:4, 1-Timothy 1:9; Titus 1:14). They are "profane," because leading away from "godliness" or "piety" (1-Timothy 1:4-7; 1-Timothy 6:20; 2-Timothy 2:16; Titus 1:1-2).
exercise thyself--literally, "exercise thyself" as one undergoing training in a gymnasium. Let thy self-discipline be not in ascetical exercises as the false teachers (1-Timothy 4:3, 1-Timothy 4:8; compare 2-Timothy 2:22-23; Hebrews 5:14; Hebrews 12:11), but with a view to godliness or "piety" (1-Timothy 6:11-12).

Like those who were to contend in the Grecian games, exercise thyself unto godliness - Train thyself up in holiness of heart and life, with the utmost labour, vigour, and diligence.