Regular guitar practice is something that each and every student needs to do to re-inforce their weekly lessons and ensure that they get the most from their instrument.
Playing guitar on a computer game is nothing like playing a real guitar and students need to understand that commitment and determination is needed to master the guitar. This doesn't mean that you should loose the fun - but if you're paying money for something you should be trying to get the most from it.
Younger Students
Practicing doesn't need to be hard or daunting but parents do need to take an active role in their childs learning.
Like all forms of homework, younger students will need to be prompted and reminded to practice as they don't have an understanding of the self discipline needed to learn (especially when the initial thrill has worn off).
Once they have been practising consistently for 6 months it will become second nature and habit, and parents won't need to remind students to practice as once a child becomes confident they'll continue to enjoy it, but this does takes time and effort.
Beginner students
Need to be practising 10 - 15 minutes, 6 times per week in order to progress.
Intermediate / Advanced students
Should be practising from 30 minutes to 90 minutes per day in order to keep their skills and improve.
Tips
The best time to practice is first thing in the morning, before you start your day and have to face all your other commitments.
Try to practice when you're not tired - you will enjoy it more.
Set small goals every practice session such as one line of a piece or 4 bars etc - setting a goal which is too large will lead to frustration and stop you practicing.
Always listen to an audio recording of the song your're learning - it will inspire you to practice, improve your aural skills and help you feel the timing of the song you are learning. In class you'll notice that the students who do well and are progressing faster are the ones who always listen to the music they are learning.
For those lacking in motivation:
Try to remember the reasons you started learning guitar in the first place - what inspired you (you saw a great guitarist, went to a great concert or have friends who learn who inspired you). Remember your dreams and goals and keep working towards them.
Listen to some music you think would be the ultimate for you to perform on guitar and picture yourself performing that piece of music. Unleash your inner rock star and visualise yourself playing the piece of your dreams.
Go and see some live music to inspire you.
If you still lack motivation, keep coming to lessons as you will always learn something new which might trigger some inspiration. Don't quit - just keep on trying!