In a matter of weeks I'll be 50 and have spent the past decades growing as a software engineer. My advice; 1st, take a deep breath and calm down, 2nd, ask yourself what you love about this career and focus on that. I've been doing this for going on 30 years and have been an ambitious, eager to learn and driven person my entire life AND will never, ever know everything I want to know or everything this industry has to offer. But, kiddo, that's absolutely ok. Ask yourself what kind of engineer you want to be; an '-' engineer who has an incredibly broad spectrum of knowledge, a 'I' engineer who knows one thing really really deeply, or more of a 'T' engineer that has a pretty broad spectrum of knowledge and an deep understanding of one technology. Then, plan your course. Take a page out of agile development to maintain your personal sanity; define a 1-month goal, then define a series of 1-day tasks that'll get you there. Be reasonable with your expectations and work through your task list. You'll begin feeling accomplishment as you chip away from the tasks and you'll see progress. That, in itself, will reduce your stress (I believe). As I'm closing in on 50, and my own learning speed slows, it's counterbalanced with the ability of applying new technologies and knowledge with existing knowledge and fundamentals. Consider this; an experienced pilot is likely quicker to learn a new aircraft than an inexperienced younger pilot. I believe knowledge workers have the same advantage. Keep you chin up, plot a course, execute your plan and keep your eye on the ball.