After knee surgery I experimented with going ultra-light and realized I really like feeling good at the end of the day, even if it means sacrificing camp comfort. Those things that you don't need, but are kinda nice to have, add up quickly.
I did a couple experiments to see what I really need on trips, but I'm sort of a masochist/type II fun kinda person so it's not for everyone. I went on a one night, then a two night trip and brought nothing but a space blanket and a knife (and a fishing pole for 2 nights). Sleeping on branches under a space blanket was better than I thought and I now use very light sleeping bags with a cheap space blanket overtop. You'll realize you really don't NEED hardly anything, then work your way up deciding what weight is worth the comfort. Last summer I did the Rae Lakes loop with a fanny pack and had a great time. Thinking surviving, not backpacking, is a good way to start. Then add to your list as desired.
I kind of cheat though because I have this list that I've used so much it's almost committed to memory. This and a fishing pole brings down the weight
The biggest gains in weight, that I think are unnecessary, are carrying any water at all, camp shoes, too much clothing, too much food, a filter, a bear can, and a tent. I've trained my stomach to handle chugging an entire liter at once so I don't carry water (with some obvious exceptions). It hurts for 5 minutes and then saves tons of effort.