Veteran cyclists know that while they still must work hard to move along at a good pace, they get better at it with experience. They develop stronger leg muscles and more overall stamina. They pick up techniques that improve their efficiency, learning when to shift to what gear, how to deal with head winds, when it’s wise to slow down, etc. They still work hard to cover ground, but they find that they get farther, faster, and with less fatigue the longer they've been riding.
Veteran disciples experience the same dynamic; they get stronger the longer they walk in God’s ways. They develop spiritual muscle allowing them to more easily deal with tests, temptations, and difficulties that would have been harder to conquer earlier in their walk. As their trust in God grows, they are able to weather longer periods of adversity; they grow in spiritual stamina.
They also grow in specific spiritual disciplines—prayer, time in the Word and in Christian community—that help them more effectively cover the course God puts before them. While there’s no doubt that experienced disciples must still put real effort into their walks, and that their paths become more challenging the further they go, it’s also undeniably true that the Holy Spirit makes them better able to deal with those things the longer they walk with Him.
That pattern is reflected in scripture. Moses started out hesitant in Exodus chapters 3 and 4, but grew increasingly strong as he followed the course God laid out for him. Jesus repeatedly, and in different contexts, taught that “[a]ny one who has will be given more [.]” Matthew 13:12 (New Jerusalem Bible). See also Matthew 25:29; Mark 4:25; Luke 8:18 and 19:26. Peter went from denying Jesus on Good Friday to boldly proclaiming Him in very threatening circumstances. See Acts 4:1-22; 5:29-33,40-42.
Just as there’s no denying that “[i]n this world you will have hardship,” John 16:33 (New Jerusalem Bible), there’s also no doubt that God increasingly strengthens those who diligently follow Him.