Haven't been playing all that long... It can sometimes take me up to an hour of practice/messing around before things start to click and my playing sounds anywhere near decent! Very rarely (if ever) can i pick up the guitar and right away start off where i left off the last time.

How long for you?

And why is it that some days you pick up the guitar and can hardly play a thing - as has been happening to me the last few days!
If you have a good solid warm up routine it shouldnt take that long. Let me ask how are you warming up? My warm up lasts about 20 minutes and gets my hands back to where they were the day before. About the days where we suck, its usually caused by stress.
to warm up i just run through some riffs from songs or exercises i came up with or learnt somewhere...they're usually geared toward stretching the left hand and getting a constant picking motion with the right....usually takes me about 20 or 30 mins or messing around like that to get to how i normally play...
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i like a nice 15 minute warm up with finger stretching and wrist speed exercises
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If you haven't been playing that long it's bound to take you longer as your muscle memory needs more time to develop. Just keep at it and it'll gradually become easier.
try literally warming up your hands (hairdryer), then play some beginner songs followed by more and more advanced pieces until you are playing your best
I've been playing for hours a day, every day, for years, so most of the time I can pick up a guitar and play decently from the moment I pick it up- though for me to really get rocking and 100% warmed up it can take anywhere from 5 minutes to 20.
I hate doing standard warm-up exercises, normally I just will play a simple song that gets my fingers moving.

And I still have those days too. It sucks but I doubt they ever go away.
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I just mess around for about 20 minutes. And everybody has their off days so don't worry too much about it.
Quote by geetarmanic
And why is it that some days you pick up the guitar and can hardly play a thing - as has been happening to me the last few days!

I really wouldn't worry about it; I've been having a bad week lately but the past few hours I've been really burning again so just keep playing through it, you'll have good days again.

To warm up it takes anywhere from no time at all to a few hours depending on what you call "warmed up", I can play all right from a standing start but to be really at my best it takes at least 10 minutes of real "I'm thinking about this shit" warm ups.
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I never need to warm up, even when I'm just waking up in the morning. I guess it's just an ability some people have. Then again, I don't know if my playing guitar from when I wake up until when I go to sleep has anything to do with it.

I wouldn't be discouraged.
I usually play, getting faster and faster with riffs for bout 20 mins till my fingers hurt then stop
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