If I have one piece of advice to give you all about what to search for in your quest for What Next, it's to find where the line blurs between hard work and happiness for you. To find that thing where working hard at it makes you happy, and where you're happy to work hard at it.
I've never had a moment when I thought: "Tom, you've made it!", and I don't think I want to, because that feels like you've reached the end; that you've crossed the finish line. But to me there is no end. An achievement is not a finish line; it's a checkpoint on a far greater journey. It's a moment to pause, to take a breath and look back and enjoy what you've experienced and be grateful for it, but then to turn around and look towards the next checkpoint, the next achievement.