A good or bad knife can make or break your day. I equate the quality of a knife to the quality of an Internet connection, if you were working in the tech world: We rely on it to do our jobs.
Think about how you'd hold a paintbrush or a baseball bat. Instead of squeezing it, hold it freely. It's all about feeling the balance while cutting; the knife should almost be an extension of your hand. True balance is not holding it too tight or too loose so it slips.
The 8-inch Shun Tomato knife. It's specifically for tomatoes, but you can use it to make super-thin slices of stone fruit, like plums and peaches. It's also a good knife for peeling a kiwi. It holds a great edge and I reach for it more than I ever would have imagined. Also, I bought my all-time favorite knife in Germany years ago … it has a long, thick blade that lets you peel just under the skin of any fruit. My most-used is my Shun and Wusthof 6- and 8-inch French knives. I have Henkel commercial knives, too. They're very accurate and long lasting, and I know they will work for whatever I'm cutting.
It's important to only use certain knifes for certain tasks. For chopping and slicing, use a sharp 8- to 10-inch French knife. For peeling smaller fruits, use a smaller, thinner blade (what I call a "fruit knife"). For slicing roasts and meats, chicken, or raw fish, use a thinner slicing knife. For decorative vegetable work, use a 4- to 5-inch paring knife. Same thing goes for peeling; I'll use a paring knife if it's thin and sharp enough, versus using a peeler.
They should last a lifetime. But you will know it's time to move on when the knife has been sharpened so much it's the width of a straw. At that point, it's too thin and not effective anymore.
I sharpen them once a month or so, but to what degree depends on what and how often I've been cutting. I only use a ceramic honing steel and a water stone. I really don't like using oil when sharpening my knives because it's messy and water is cleaner and better for the environment.
Peeling and julienne. There's also a term called "turning veg," which means shaping vegetables into logs, similar to football shapes. Although I don't do it often anymore, it reminds me a lot of pottery, like working with your hands.