If collecting some sets becomes a hassle, consider stopping ? As for me, I wait to see the scans of each cards of the next set before deciding to buy anything : I'm not going to spend time and dozen or hundreds of $ (well, €) to buy cards I don't find appealing. And searching for one specific card, waiting to find THE deal is part of what's so exciting about collections. I also often check my folders to watch my cards, I remember how I got them, I take them out of the folder's sheets to watch them closely, to enjoy their details... I never get bored of them.
I collect mostly recent sets. I know that the appeal of ancient sets is mostly nostalgia (to me, at least) and that I will be quickly bored collecting them (I find them less elaborated and less colourful in some ways). But some prefer the old ones. Or collect only RH, or one kind of Pokémon, there's several ways to collect !
As said before, try to find what you really like collecting, try finding cards you didn't know existed (promos, some Japanese sets never released outside of Japan, etc.)