I've also heard the "stupid tax" or "dumb tax" as what you pay when learning or doing something new. There will be times that you look or feel like an idiot, but we've all been there, don't let it stop you. Learn from your mistakes and persevere. You're never too old to keep learning - knowledge, skills, compassion, empathy, shame, regret, success, failure. Life's a trip, appreciate it for all its aspects and keep at it.