To be honest Nick, welcome to old age. Things change so does your body and your mind. Chemicals that once allowed you to deal with stress are diminishing. Even one's that give you that drive are too. We all get this way as we grow older some worse then others. So we look back and try to rengage our minds and concentrate harder but it does no good, in fact it stress us out even more.
Another thing is we see the world in a perspective which we believe should change for the better, when it doesn't after so many years of watching and waiting we become impatient as we get older. The best advice I can give, is "don't sweat the small stuff, it's all small stuff!" Maybe going to the shrink might give you some new avenues to explore or a different take on life in general. Dispair really, or just depressed? Dispair is a desperate state of mind. Depressed is not so bad, we all get depressed. What would you have to dispair over.
1. You have a beautiful wife who loves you and enjoys your company. You have allot in common and I would say that you love her also, deeper than you think.
2. She shares in your triumphs

and your grief!
3. You sound as if you feel good about your work and have a sound job.
4. You obviously are not in a financial delima or in a bad way.
5. You are healthy.
6. You have interests which obviously make you happy.
7. Your not threatened or fearful of anything substantial.
8. You have friends who you enjoy!
9. Your life is stable.
10. I would imagine you have a good retirement awaiting and you have a dwelling.
My question to you is what are you looking for? What are you missing? Are you content?
Think about what I've said and I believe that after you look at what you really have, your quite wealthy. Maybe you just need to sit back and let the world be what the world is going to be. Nick, I thought I was going to make a big difference in the world by being a soldier and saving lives. Being risky and taking extreme risks. I finally realized I didn't know anything, really. I was pushing so hard and so fast my life was litterally flying past. Then a little bulb went off in my head. I'd had everything in my life that I ever wanted or dreamed about and it didn't make any difference. What did make a difference for me was the things I had overlooked. Love with a woman who loves me. A home to share our love in. Food on the table every night. A bed to sleep in beside my lovely wife. My two children, even my two Cocker Spaniels. I'm still healthy, alert and mindful of who I am and I still haven't decided what I really want to be. My to do list is ever increasing because as I grow older I know I'll never get it done, so big deal.
I have lost one's I've loved but I remember only the love shared. Nothing else really matters. I will love until the day I die, and it will probably be all I'll be able to take from this world.
So, look at what you really have and eliminate what you don't really need. Smile more each day! Lend a hand to a stranger when you can. Slow down and make sure you laugh and chuckle more. Practice being at peace with yourself. That's what counts.
Cheers
Jeff