I've been playing guitar for around a year and a half. I've been trying to practice for at least 3 hours a day and can usually practice at least an hour. Even in that hour, I'll usually get distracted by the internet or something and I need the internet for my source of tabs. Any advice to keep practicing effectivley? I just turned 14, I don't want the days to go to waste.
Sounds like focus problems. You just need to keep telling yourself if you don't practice you'll never get better, but even an hour a day is good.
Well there are other ways to learn guitar than tabs. How about you print out a chord sheet and try to memorise them all?

Also picking exercises while watching TV are pretty common - "hey honey - can you move over a little? The guitar neck needs to take your place "
And no, Guitar Hero will not help. Even on expert. Really.
I'm not trying to discourage practice whatsoever, but don't push it man. I understand getting distracted but if you don't feel like playing, then take a break, otherwise it may be detrimental to your actual comprehension of what you're doing, let alone the enjoyment aspect. It's great to have goals, but if you're checking the clock every 5 minutes to see if your practice hour is up, you're pushing it too hard.
If the guitar is not fun, put it down.

On the other hand, I'll sometimes sit around with my guitar around my neck for 7 hours but only play for 3-4 hours. lol it happens...
Oh yeah.

Quote by hildesaw
A minor is the saddest of all keys.

EDIT: D minor is the saddest of all keys.
1) Chop up your practice time over the day. Dont think that because you have 3 hours a day to practice, you have to practice for 3 hours straight.

2) Take breaks, your head and hands need rest now and then. That 15 minutes every hour you give yourself to recover will improve your playing more than 15 minutes of practice with your concetration gone and your fingers struggling to keep up.

3) Use variety in what you practice. Dont just do the same thing everytime, try to do or learn something new everyday. Dont practice one thing for more than 15 or 30 minutes, do more than one thing. Use different sequences of things to practice.
Dont get stuck in a routine! The mind and body learn more when they are confronted with things that feel new rather then too familliar!

4) Allow yourself to screw around and have fun now and then. Give yourself some time to play to backing tracks or just songs or just play random riffs. Dont get stuck in making the guitar a chore, you need to keep your motivation.

5) Be realistic in planning your practice sessions. You might wish to be able to play 4 hours a day, but if you only have the motivation / energy / discipline / concentration for 1, it's no use. It doesnt matter how many hours you play every day, what matters is *that* you play everyday.
It's better to be able to play an hour a day for the long run then whole days and burn out after a few weeks.