We've been 4,000 miles, an ocean and 5 hours timezone difference apart for the last 2.5 years now... It's challenging, and very expensive (travel wise).
But we love each other and are moving towards settling down in the same place, so there is definitely light at the end of the tunnel.
We do make the time maybe 5 days a week to watch some TV or movies together, or play a game on Xbox Live or Steam together or something, but sometimes the timezone difference and our schedules screw us and we don't get to do talk or see each other even virtually for 2-3 days.
Those days are definitely where you need to take special care to at least stop for 5 minutes during your day and message each other over IM or email (even really just to say good morning or good night), otherwise things can go very wrong. The few arguments / fights we've had have been either caused or catalysed by one of us being out of touch for too long (usually me to be honest).
The timezone difference is the most consistently difficult part for us actually. 5 hours is a lot during the week - one of you gets home from work at 6pm and has to wait until 11pm their time to do anything. The other ends up being alone from 7pm their time as their SO had to go to bed.
I am lucky enough to have a decent job where I can afford to buy some long haul plane tickets and hotels every 2-3 months, which has been a big benefit for us. I think the longest we've been without seeing each other in person is 4 months - if we had to go much longer than that I think it would become exponentially more difficult. Typically we get to see each other for a long weekend 4 times a year, and a bigger 7-10 day trip once a year.
That all said, the technology involved is amazing these days. 10 years ago we wouldn't have been able to do free international voice / video calls so easily and with such high quality, and the bandwidth and services weren't there to allow such smooth watching of streaming movies and TV together. It was even difficult playing real-time games with people over such distance due to the latency involved. These are huge, huge things when you're so far apart... These kind of broad technological advances haven't magically made online interaction the same as being together in person, not even close, but it can be enough to keep you going until you are.
As others have said, if you're looking for advice here - it really is all about communication and making the time to chat regularly, and I mean every single day if at all possible. Even if it has to be brief some days. You really have to actively engage in that way more than you would if you were living close together... Don't ever sit around waiting around for them to initiate it, just pick up the phone / tablet / keyboard / whatever and do it. If you know they are busy and can't reply, drop them an email or leave a voice message or something.
You also have to find ways to express vocally what you can't physically (and I'm not just talking about phone sex haha) - like you can't offer a nice simple hug when your SO is down, and that fucking sucks every time. But you can make sure your tone is sympathetic, and support them with your words. You can still goof off and joke around when they need cheering up, you can still surprise them with a little gift here and there, and you can still listen when they just had a shitty day and need to vent.
You can also make sure that neither of you is ever left battling a problem all alone, whatever it is, just talk about it and figure it out between you. Even if they can't directly help due to the distance, having your SO there even just as a sounding board and a non-judgemental moral supporter can go a hell of a long way.
These are the real cornerstones of any relationship in my opinion, and having that person there for all these kinds of ways is what prevents the physical loneliness from destroying you.
If you're truly serious about being with this person, you should also start making some kind of plans for how you can be together long-term. Because a long distance relationship isn't possible forever, so don't fool yourself into thinking that it is. Even if a future together seems far off, or scary, or difficult, or there's a million things standing in your way... Developing some kind of path ahead of you which will bring you both together is very important. It will also give you both something to work towards. As you start knocking down all the little obstacles in your way over time, it gives you both a real sense of progression in your relationship - that this whole thing is actually going somewhere and you're not just wasting your time or spinning your wheels - it stops you both feeling so trapped by circumstance.
Anyway, I've rambled on enough! Just remember that nothing in this realm is impossible if you both want it to work. Best of luck getting there.