some people find it easier than others... I know people who have a hard time keeping it tucked for long times. Sometimes you have to ease yourself into it.
You might not wanna do it 24/7 and not be tucked at night to let things breathe, as keeping everything really compact can cause a few issues such as infections, pain, and the possibility of nerve desensitization.
Also, some people find that pads (as in feminine pads) are helpful for tucking in a few ways: One, it helps keep things in place well, but also helps provide some extra comfort. Two, it absorbs moisture. Moisture is bad, as you can find you can get infections (bladder) and rashes... which aren't comfortable. Oh, and three it makes things appear smoother down there, so if you're say, wearing something tighter there's no bump.
I know the pad thing probably sounds weird, but when I tucked I used them and it worked well. Just use the regular size ones (like, Always brand regulars). I know other people that used them and swore by them as well.
Take your time, and don't over stress it down there. If you're in pain, you're doing it for too long. Start off with a few hours a day, then go for half a day, then go for a full day until you get used to it. Over night is usually not recommended, as I mentioned... And, oh yeah, erections equal pain, just to warn you. LOL