Get a list of what you think you need, then cut on half. After about a 25 lay off from back packing, I started back at the age of 44 and soon learned that a 44-47 year old man can not carry a 40 pound pack. I try to keep my packs under 21#s. Some things you need are
1, some way to filter or purify the water.
2, stove, a fire ban can ruin your trip if you don't have a stove. I use a jet boil, cup and stove together so I don't have to bring a cook kit.
3, First aid kit
4, light, I prefer head lamps.
5, tent or hammock
6, sleeping bag
7, RAIN GEAR.
8, I don't use waders, but good wadding sandals or boots.
9, I carry wind walker fishing pack, but tend to leave it at camp and stick a fly box in my pocket and hang tippit and clippers on my shirt.
10, Backcountry permit. I have been checked 3 times and each after the trip with a ranger sitting in the parking area when we came out.
11, I bring my 15yr old son, so I can load his pack down with the stuff I want but don't need. HA HA
12, I do bring bear spray, because my wife makes me. But it is better to be safe.