It’s a lot easier to exercise when you weigh 30 lbs less. Runners claim more than 2 seconds per mile per pound.
I've gone from fit and powerlifting for years to fat for years to trying to get back into lifting, etc. (the latter, multiple times) and while age is a bit of a confounding factor, the fatter I am, the more difficult exercise is - both cardio and resistance training. It's just harder on your tendons and ligaments. It's not insurmountable, and training can make those more resilient as well, but when you're starting from effectively zero, doing that a 250lb is tougher than doing it at 200 is tougher than doing it at 175, etc.
Running is pretty high impact, too. It's going to put quite a lot of stress on your joints.
I'd recommend everyone incorporate exercise as much as they can regardless of their weight, but I've found it easier and easier to ramp mine back up as my weight has gone down.
Presumably now that you've gotten into powerlifting you don't still lift the same weight you did when you started. If you did, it would indeed be easier. But you probably lift more weight, so that the intensity is similar.
(To be completely transparent, I wasn't trying to state a universal truth. That phrase is just a common tongue-in-cheek joke among runners and cyclists; I misread the crowd a bit assuming it'd be recognized)
There are a lot of people that seem to think that obese people can fairly easily just stand up on day one and start working their ass off, though, and that this is the only thing holding them back from changing their lifestyle, so I made the faulty assumption your comment was along those lines.
(These days I'm thinking I'm going to be move towards being more focused on the hypertrophy aspect - less likely to injure myself, and I gotta do something to fill out at least some of the loose skin that awaits me on the other end of the weight loss journey)
If you take someone with a fixed fitness and reduce their mass, they will expend less energy per unit of time, but in order to effectively train you need to keep a target intensity, so you increase the amount of distance you cover per step or increase your cadence, either / both of which increases the energy consumed per unit of time.
That's all I mean when I say that you just go faster.
In my experience, qualitatively, what you say is absolutely true. I don't even notice a change in pace if my weight floats up or down a bit, I mostly run at a specific level of effort and the pace adjusts itself depending on how much I've over-indulged. However, there are thresholds.
If I try to run a pace that is too slow, there's a point where it almost becomes more shuffle than run, gait goes to hell, and there's a loss of efficiency. As I've gotten more fit (but not lighter) I can now do zone 2 running on the flat with workable form, but this wasn't always the case. It's still less efficient than a fast pace, but at least it looks like running.
So if one is too heavy to even run with actual running form for any length of time, it's harder to be heavy. That's okay, they should probably try run/walk intervals until they get there.
On the other hand, it can also be harder when you're more fit. My pain tolerance has gone way up. I can just beat the ever living snot out of myself, and if I'm not careful, I do just that. It's much easier to do too many miles way too quickly now and that starts manifesting itself in all kinds of noisome ways. Find anyone who considers themselves a runner and get them talking about their injuries and you better not have anywhere else you need to be.
By your definition, Usain Bolt running the fastest 100m time ever set by a human is having an easier time than me because I do it slower.
What most people mean by easier is that it "feels" easier: this would be accomplished by aiming to take the same amount of time even in the face of capacity increasing.
It's not just a comparison of fast versus slow, it's also heavy versus lighter body weight. You can move faster at lower weights while spending the same amount of energy as someone moving more weight slowly.
The net result is that it's easier to run a fixed distance when you're in shape. The same energy output makes you move faster, making the run shorter in time duration, meaning you actually spend less energy.
Further, getting in better shape often coincides with improvements in metabolic efficiency, so you get further benefits.
Usain Bolt has exceptionally improved musculature and metabolism for sprinting over the standard person, so his maximum energy output results in an exceptional speed.
At that point, we aren't talking about equivalent energy outputs anymore, which means it isn't relevant to the "easier" qualifier.
The wrinkle is that most runners run to a pain point. Over time, I went from neverrunning to running decent mileage per week, and my runs hurt _more_ now than they did when I started because I run to a pain point. I run further, faster, and more frequently and I have a higher pain tolerance, so it hurts more while I run and the recovery is rougher.
So my runs are at least as hard, but yes, I'd absolutely destroy the version of me that thought three miles was an accomplishment by any objective metric.
work = force * displacement
work = mass * acceleration * displacement
lower mass, less work.