It doesn't always feel, in the moment, that we are growing, or have grown. But I think those moments of reflection and looking back on my life and the fluster of remembering 'Wow, I really did that?" or "I can't believe I was like that..." and comparing the who I was, to who I am now in Christ often helps in those moments where it feels like there is no momentum in my walk. I realize that, perhaps, in time, be it a year, years, or decades from this moment, that I may very well be looking back on this time as an embarrassing blip of my youth. It is hard to see growth framed in the context of our lives, when we are at any moment living it presently, and can only see limited distance in front of us.
People are also so variable with the sins and passions and vain labors that we may struggle with in our lives--we cannot cookie-cutter match up what a growth in grace looks like in our lifespans to others. I think sometimes it is not so much a linear growth model, so much as a best fit line--wherein the data points may lead us down and up and down and up, yet we should hope we are overall progressing upward, even while particular deviations in the graph may be regressive. This is why we continually come before the feet of Christ, why we must continually humble ourselves and repent--because we may have the same struggles at 70 that we do at 15, but over time and with training in the way that we should go, when those latter conflicts arise, the spiritual exercises that we have been building throughout our lives may "kick in" as a natural instinct, because we have been conditioned by the Spirit.
Again, it is helpful to look back to past times where God has graciously brought us through circumstances, reproved us, aligned us, conformed us more to His will--if He managed then, He will manage now, and continually throughout. So, when it comes to something like "what are the marks of growth..." I think an easy, practical exercise is to reflect on the past, and see how I would react to situations in manners then and how I do now--comparing a youth in Christ, to a more mature me in Christ. A personal example is of my temper and volatility, uncharitability and disreprectfulness--even while I professed to be a Christian, I used to get extremely riled up when I perceived a wrong, or slight, and always felt it my job to correct such a thing--this was easier with loved ones who I disagreed with (even for good reasons), and I would act rashly and unlovingly toward them. I have been many years separated (distance wise) from much of my family who always perceived me as this raving hothead. It was something I had not thought of much until I had gone home for a visit, and had to deal with truly tense familial and social situations, and my brother expressed how surprised he was at how I interacted so peaceably and charitably in the situation, and my mother (of all people!) expressed that she expected me to come out with torches waving! In one sense, I was hurt that that was the picture of Christ that I ever put off as a professed follower, but on the other hand, I felt so full of grace and mercy that this was not me now and that--seemingly under my nose--God had changed how I was wired to interact with these sorts of situations. This is just a small example, but I think it holds--we can see growth when we compare like-situations (and, often, it does seem God places us in them again and again as exercises)--we get to see how walking in the Spirit looks quite different from when we began to the journey, to now.
And, more succinctly, to think about how one grows in wisdom--it begins with knowing the law, and meditating on it, for without the law, we do not know our sin, and without the acknowledgement of our sin, how could we ever fully embrace the wonderousness of grace given to us? Throughout the Scriptures, wisdom begins with the fear of the Lord. We gain it through the working of his Spirit. For many, it is ordinarily something to be 'trained up' as in the Psalms--and so comes through understanding the law, attending to the means of grace (preaching of the Word, fellowship, Sacraments, prayer); in places like Ecclesiastes it may be learned through life experience, as the Teacher comes to gain wisdom by first stumbling through a life of frivolities (but also as students to him, we can learn this lessons by learning the experience of another, and not having to go through it ourselves); in James it involves constantly working out in our daily lives the ways in which we practice wisdom in our words and actions which reflect the nature of Christ; and, so, the ultimate wisdom IS Christ, the perfect embodiment of God's wisdom nature, and so Christ is the source of all wisdom, and we look to him for it.
