Is it possible to use meditation to gain Self control? I have planed my life and want to stick to it . But the problem is 
My self control . 
For example I tend to waste a lot of my time in youtube watching documentaries . 

You know it starts like I 'am going to do this for only 30 minuets and then loose the rest of the day watching videos or etc.

I was wondering if meditating on my future goals could help .

And I mean doing something like imagining how it would feel if achieved my goals and then imagining the consequences of wasting my time or uncontrolled life . 

Is this a good method to gain self control and achive my goals ?

Is there anything else I can do ?
Self control of gained through mastery over the mind, i.e., developing Right Effort, Right Mindfulness and Right Concentration in the Noble Eightfold Path.

The lack of mastery over the mind would lead to you losing the sense of time when doing this activity. One thing you can do is be aware you are are doing this and the sensation that watching videos bring. It is the feeling and sensation of excitement and the intellectual stimulation documentaries bring which keeps you doing what you are doing. If you get less attached to this you find it easy to switch to another task. So be mindful if what you are watching is perceived as or evaluate as positive (intellectually stimulating, interesting, keeping you in suspense to know more, etc.), negative or neutral and the sensations that follow which are pleasant, unpleasant or neutral, maintaining utmost equanimity, and being aware of the arising and passing of what is felt (the particular sensation / feeling that is felt). [Sal-āyatana Vibhanga Sutta, Indriya Bhāvanā Sutta, Pahāna Sutta]

In addition to the above, at a more mundane level, it would be helpful the be mindful of the time as well by having a clock placed near the screen which can help you keep track of time.