Well... I used to be a mechanic. Exactly 40 years ago, I completely disassembled my pride & joy - a £70 XK120 - and modified or replaced with different equipment, every single component except the door locks. Since then the only times I have taken a car to a garage was when I had fuel injection problems.
In November 2003, when I was 57, I was lying under my Golf Git fixing the clutch. I was tired, oily, frozen, and had managed to remove the skin from a couple of knuckles. I decided at this point I had had enough, so after buying the LS the following summer, I now drop off my car and fetch it when it is fixed. (Not quite true, I did adjust the headlamps and also replaced a front air dam which I then busted again about two weeks later.)
I may save money if I did stuff myself, but I have never regretted my decision to 'retire' from intense car DIY.
Perhaps one or two fellow members will have made the same decision ?