I probably wasn't feeling as much apathy as you, but when I was 29, I was in a great job with awesome pay and perks and was moving up the corporate ladder. I had no kids, no house, no major responsibilities and life was moving according to the script. I had lot's of great friends, liked the people I was working with, was in great physical shape from all the working out and I was using my university education which seemed to make sense.
After 3 years in my newest role I realized I wasn't happy or being challenged enough in every facet of my life. I could literally play/teach billiards every day in the staff lounge for 3-4 hours and still meet all my work targets. My hobbies even ceased to challenge me the way I needed. I was no longer meeting anyone new that challenged me. I didn't want to be indoors any more working under fluorescent lights in recycled air, and going to a gym in recycled air - I wanted to sweat and get dirty every day and feel like I was doing something meaningful.
The strange thing that spurred the change was that one day I was riding the subway home work and saw one of those free "employment news" on the seat beside me. I picked it up wondering what kinds of stuff was going on in the job market. When I opened the paper, the first thing I saw was an ad asking "Have you ever wanted to work in a greenhouse? Have you ever wanted to work with plants and trees and build beautiful gardens? If so, maybe an apprenticeship in Horticulture is for you!" I immediately realized that I wanted to be one of the largest producers of organic weed in Ontario and this education would get me there. I called the number and it seemed like a great fit for what I was looking for.
Since I was financially very comfortable, I decided to to take a leap of faith in myself and resign from that job and go back to school for horticulture. I also got my bike license right after quitting that job and also resolved to travel/backpack to at least one interesting place each year for the rest of my life. After school I immediately bought a motorcycle, got a job for minimum wage as a gardener/grunt in a high end property maintenance company and quickly moved up, but still only making around $20/hr. Even though it took me over 10 years to get my earnings to the place where they would have been (had I not changed my life direction), it was the best decision I made to try something completely new and uncomfortable and trust that it would give me the happiness/work/life balance. Even when I was not making much money from this change, I was happy.
Motorcycles became an all encompassing new hobby that was mine alone and I could develop in any direction. Even though I never became the commercial weed grower I thought I would become, horticulture became a way for me to earn a living, while doing different things and meeting people that were so different than anything I previously knew. Travelling each year became a way to meet other people and cultures that I would have normally thought nothing of. I am a firm believer that if you have an amazing work ethic and treat everyone around you well, good things will happen.
Maybe all you need is to identify and move away from the things that truly do not being you joy and take a leap of faith towards a different path in life.
My point sounds similar to your 29 year old point. If I objectively look at my life, I can humbly say I'm unstoppable and beyond the vast majority regardless of age. Every job I've risen to the point of "irreplaceable because he built everything"; it's happening again and I was recently involuntarily promoted; it's been < 7 months at this gig.
While I'm very proud of the above, I am obviously bleeding apathy and forcing myself to perform. I need to figure something out because a full career swap is financial suicide.....there's probably a clock ticking between that and a full mental break though lol
We have read similar books yes =DFeel like we might be related, that takes me way back
EDIT: Anyone read "Zen and the Art of Motorcycle Maintenance?" I had a vague understanding of why the main character ended up in the loonie bin when I read it nearly 10 years ago....makes a lot more sense now.