- A sleeping bag rated for much cooler temps than 40 degrees even if it's in the 60s at night
- A closed cell pad over any kind of air pad
- I still get sweaty even with one outfit to wear
- I still would prefer a larger tarp if the weather is going to be bad.
And yet my load is still light.
I think that new hikers who have no gear at all should start with the lightest they can get without going to any rash extremes. There's absolutely no reason to "graduate" from heavy to light if you don't have to. Much of the light stuff is better than heavier stuff anyway.
But if you have heavier stuff already, just go. Before you do, though, go through what you have and ask if you really really need it.
If it's something that is consumable, ask yourself if you really need to carry so much of it. If I'm going for a weekend, I don't bring a pint of fuel. I bring a couple of ounces. Enough to spill once or twice. I don't bring a full thing of mosquito repellent. I bring a tiny visine bottle of it. I can go a weekend without deoderant (heck a whole summer, too.)
For the non-consumables, ask a bunch of what-if questions and see if you can answer them by removing stuff and making do with something else. Do you really need heavy long underwear to sleep in? Can light long underwear and your rain gear keep you just as warm? Do you really need a cup, plate, bowl, spoon, fork and knife? Can you eat and drink out of your pot with just a spoon instead? Can you wear all your clothes at once and be warm enough, and if so, can you leave home all the clothes you can't wear at the same time? Do you really need a pillow or can you make one out of some of your other stuff? Are camp shoes really necessary if your hiking shoes are comfortable and dry quickly?
Now get out there and go! Start learning. I learned a lot hiking the PCT. I didn't know it all beforehand. I still know less than the average PCT hiker. There's a lot of stuff you can tolerate without dying. I still get to learn that lesson from time-to-time.