Inasmuch, then, as the true believers are also not just simply and primarily here to see a reward in this life, but rather for the promise of eternal life and along with that, are to commend to God the Lord how He may desire to deal with them in this life, whether He wants to lead them to heaven via roses or via thorns, whether He wants to give them cross and adversity or relief from tribulation… all this they are to willingly receive from His hand and in all things, obediently commend themselves into His gracious, fatherly hand.
This is also the Scriptural explanation given to Timothy by this apostolic rule: Train yourself in godliness, that is serium pietatis studium [the serious pursuit of godliness]. For bodily training is of little value, but godliness is good for everything and has the promise of this and the future life, that is amplissimum pietatis proemium [the farthest reaching reward for godliness].
By relying on divine help, let us and others, by responsibly following this apostolic rule, train ourselves for godliness. [Let us do it] in such a manner that we, at the beginning, search out the most important and moving reasons which should, in general, encourage and awaken each individual to godliness, which yet not everyone makes their top priority. Let us sharpen these skills. (Schola Pietatus-Volume 1 by Johann Gerhard, Repristination Press, p. 28)