Taken from Practical Directions: How to Grow in Grace and Make Progress in Piety 
by Archibald Alexander (1772—1851)

But grow in the grace and knowledge of our Lord and Savior Jesus Christ. To him be the glory both now and to the day of eternity. Amen. (2 Peter 3:18, ESV)

Growth in grace is evinced by a more habitual vigilance against besetting sins and temptations, and by greater self-denial in regard to personal indulgence. A growing conscientiousness in regard to what may be called minor duties is also a good sign. The counterfeit of this is a scrupulous conscience, which sometimes haggles at the most innocent gratifications, and has led some to hesitate about taking their daily food.

Increasing spiritual mindedness is a sure evidence of progress in piety; and this will always be accompanied by deadness to the world. Continued aspirations to God, in the house and by the way, in lying down and rising up, in company and in solitude, indicate the indwelling of the Holy Spirit, by whose agency all progress in sanctification is made.

A victory over besetting sins by which the person was frequently led away, shows an increased vigor in the renewed principle.

Increasing solicitude for the salvation of men, sorrow on account of their sinful and miserable condition, and a disposition tenderly to warn sinners of their danger, evince a growing state of piety.

It is also a strong evidence of growth in grace when you can bear injuries and provocations with meekness and when you can from the heart desire the temporal and eternal welfare of your bitterest enemies.

An entire and confident reliance on the promises and providence of God, however dark may be your horizon, or however many difficulties environ you, is a sign that you have learned to live by faith; and humble contentment with your condition, though it be one of poverty and obscurity, shows that you have profited by sitting at the feet of Jesus.

Diligence in the duties of our calling, with a view to the glory of God, is an evidence not to be despised.

Indeed there is no surer standard of spiritual growth than a habit of aiming at the glory of God in everything. That mind which is steady to the main end gives as good evidence of being touched by divine grace as the tendency of the needle to the pole proves that it has been touched by the magnet.

Increasing love to the brethren is a sure sign of growth; for as brotherly love is a proof of the existence of grace, so is the exercise of such love a proof of vigor in the divine life. This love, when pure, is not confined within those limits which party spirit circumscribes, but overleaping all the barriers of sects and denominations, it embraces the disciples of Christ wherever it finds them.

A healthy state of piety is always a growing state; that child which grows not at all must be sickly. If we would enjoy spiritual comfort, we must be in a thriving condition. None enjoy the pleasures of bodily health, but they who are in health. If we would be useful to the Church and the world we must be growing Christians. If we would live in daily preparation for our change, we must endeavor to grow in grace daily.