If you are a beginner at playing the guitar then you might find it a little difficult to start moving your fingers along the fret board. Bending and flexing your fingers all of a sudden could be uncomfortable and painful initially. A few finger exercises will not only make your fingers more adept and flexible it will also help improve your playing technique and increase your speed.
The more your exercise for fingers and train them to be more flexible the faster you will be able to pick up speed since playing and changing chords has a lot to do with the speed of your finger movements. Even strumming, plucking or playing the lead on your guitar will require your fingers to move fast and with ease over the frets and that would require training your fingers even when you are not holding a guitar. Fingers exercises for guitar playing can be done both without the guitar and with it.
As you begin to play for the first time your hands and fingers need to first get accustomed to firmly gripping and sliding over the neck of the guitar. One of the easiest exercises to get your fingers used to gripping is to use a grip trainer or a soft tennis balls. This will help you to increase the strength in your wrists and make it supple enough to bend and hold. Carrying light weights would also help to strengthen your wrists and your fingers. Other than this to help you increase your finger mobility and speed you can try this simple exercise. Place your hand on a table or a flat surface, and then lift your palm so that it is not touching the surface but instead your fingertips are stretched out and are still touching the surface. Hold it in that position for a few minutes and then slowly start lifting and lowering a finger at a time as if doing pushups. Do this for all your fingers of both hands; this will help to boost your finger independence and give you an edge when you try to pluck at the chords. For these simple exercise you don't need to have a guitar in your hand, and can do these flexes anywhere. When you hold your guitar use fingers 1, 2, 3 and 4 and slowly try to do some alternate plucking, you may start out slowly but as you keep trying it will help you increase your speed. You may initially experience strain and cramps in your fingers but as you practice you will feel less uncomfortable and slowly your finger movements will become fluid.