There are a couple things that can factor into how taut your strings are. The first being the fore mentioned tuning. This will typically effect your strings the most. Non-standard tuning, on purpose or on accident, can lead to lots of wear on strings and can make them very tight. Especially when switching back and forth.
The second is the gauge of string. The thicker the string the tighter you will have to pull it to get it in tune. So if you want lower and looser action, trying lighter gauge strings. This will also effect your overall tone as well, so keep that in mind.
The third is the setup of your guitar. A raised bridge or nut will move the strings further from the fretboard and make it seem like the strings are tighter when you're playing. Also, if your guitar has an adjustable truss rod, you action might be effected by how it is setup.
I would say you might want to take it into a shop and tell them what you want out of your guitar. Especially if it's the overall setup. I don't recommend anyone mess with their setup unless they're experienced with it, you can make your guitar a giant pain to play or in some cases even damage it if you make a mistake.