It hurts from my fingertips to my elbows. Both arms. There is a definite difference between playing around with an upright bass and getting in some serious practice. Last night I got in some serious practice, and my upper extremities are protesting. Vociferously. It's the price to be paid to get better.
The pickup I bought for the upright bass arrived in the mail a couple days ago. It's designed to fit in between the wing and the foot of the bridge, an opening only about 1/4 inch wide, amplifying the sound. The bridge holds the strings in place and transfers their vibration into the body of the bass, creating the sound. It's under about 200 pounds per square inch pressure, but the wings are fragile, and the opening needs to be widened so the pickup will fit. I need to shave and sand that 1/4 inch opening. Do I need a sharp knife? You bet I do! It needs to repeatedly glide through a thin slice of wood without pressure, till the opening is just wide enough to accommodate the pickup, holding it in place with just enough, but not too much pressure. A dull knife means a broken wing and an expensive trip to the luthier.
Our life with Christ is like that. If we are sharp, we are useable in God's hands, able to effectively use the Word of God to "divide between soul and spirit, joints and marrow, discerning the thoughts and intents of the heart" (Hebrews 4:12). But if we get dull, our effectiveness diminishes and we can even damage God's music.
When I was preaching, I had to be sharp; Sundays came around with amazing regularity and I had to be ready for them. In retirement that's no longer the case, and lately as I was reading some Scripture, God nudged me. "You're getting a bit dull, Jim." The blades of my heart and mind need to be sharpened if I am to be effective for God, so it's back to real study. Part of me doesn't like it; real study is real work, and I kinda like the easier path of retirement. But I don't want to get to the point where God has to choose another tool to get the job done, so I've got to figure out a schedule for study. I am thankful tonight that God used a musical instrument to teach me a lesson, even if I'm not thrilled with the lesson itself.