It's not that bad if you know what you are doing.

A mower bag is for collecting leaves not grass clippings. If you are not picking up the clippings it's a ton lighter and easier.

Mow at the correct height of the grass species. My lawn is PRG and TTTF. So I put the deck as high as it goes. This makes it a ton easier to push.

Sharpen your mower blades at least yearly. It doesn't take long and really makes things easier.

Mow more frequently if possible. When the grass grows faster in the spring and fall, I often mow twice a week. During the heat of the summer I might only mow every 2-3 weeks as the grass grows slower. Not pushing the mower through thick overgrown grass cuts down on the work.

If you get behind and the grass is tall (like after a couple weeks vacation), walk really slow, and only take half swipes. This lets the blades do their thing without overloading them.

Fertilize only in the spring. If you don't pickup your clippings this is enough the the entire year.

Those assisted ones are usually heavier and quite a bit harder to push than a normal push mower when the drive system craps out. I had one that happened to, and it was definitely a workout compared to a "normal" mower.