I noticed an immediate difference too.. in physical appearance which rarely happens for me at first.
I had these pesky “love handles” that I have been trying to get rid off for a min (the spare tire from years of drinking) and rowing wasn’t the ONLY thing I was doing, I just increased my output strictly with that and noticed the immediate change almost a few days after the 3 hour row.
I am also taking certain supplements, back on my high protein/med carb and lowfat diet, basically cut out drinking (maybe a day or 2 here and there past few months), significantly increased my water intake (bought a free-falling water purifier that I probably have to refill like twice a week), and was still in the gym while adjusting from full body workouts back to focusing on specific sections of the body and specific body parts.. mainly to rest other bodyparts and reduce injury and while increasing frequency.
Not sure how long I will keep it up but it’s time to take it serious again.