I've been cooking for long enough -- more like overcooking for long enough -- that using a probe thermometer felt like I was giving up. Like I stopped caring and started wearing sweat pants out of the house. I told myself I should be able to do better. I told myself I had experience. I should be able to put my thumb on a piece of meat, immediately gauge how firm it is and declare: medium rare! Then I would deliver it to the table and there would be deafening applause.
I got over it. I use a probe thermometer regularly now. I can vouch it works; when you don't overcook things they taste way better. The pork loin. The hunk of salmon. The chicken parts. I even used it on the first steak to pass through my door in half a year and it came out perfect, though there was a distinct lack of applause.
Invest less than ten bucks in one of these. It'll make you look like you know what you're doing. It did for me. Finally.
One note. Most thermometers recommend cooking pork to a temperature that renders the meat criminally overcooked and tough. I cut it back by several tens of degrees, and, while I have yet to catch a fatal disease, the pork has been way tastier.