Hard time on rollers

I bike 30-60 minutes on my fuji declaration at about 25kph when on a trail, so I figured rollers would be a good option for indoor training. But honestly this feels like a replacement for leg extensions rather than outdoor riding. I can go about 5 mins and then I'm gassed. Is this how it's supposed to be?

I bought the $100 cycling dream rollers on Amazon. Front roller is slight ahead of front skewer. I'm about 200lbs. Using it on hard floors also.