Hi,
Welcome to the forums!
I once used to be worried about this very thing.
Just because watching TV is not glorifying God directly does not mean that it is a sin. When we are saved, by no means is our free will limited. It just means we have a greater choice, which is we are now free from sin, and can choose to resist the devil, whereas before we could not.
Remember what Paul said:
1Cr 10:23 All things are lawful for me, but all things are not expedient: all things are lawful for me, but all things edify not.
1Cr 10:24 Let no man seek his own, but every man another's [wealth].
1Cr 10:25 Whatsoever is sold in the shambles, [that] eat, asking no question for conscience sake:
1Cr 10:26 For the earth [is] the Lord's, and the fulness thereof.
1Cr 10:27 If any of them that believe not bid you [to a feast], and ye be disposed to go; whatsoever is set before you, eat, asking no question for conscience sake.
1Cr 10:28 But if any man say unto you, This is offered in sacrifice unto idols, eat not for his sake that shewed it, and for conscience sake: for the earth [is] the Lord's, and the fulness thereof:
1Cr 10:29 Conscience, I say, not thine own, but of the other: for why is my liberty judged of another [man's] conscience?
1Cr 10:30 For if I by grace be a partaker, why am I evil spoken of for that for which I give thanks?
1Cr 10:31 Whether therefore ye eat, or drink, or whatsoever ye do, do all to the glory of God.
Basically, whatever we do, we do it FOR the glory of God. Just because it does not directly glorify God does not mean we cannot use it for God's glory. This means that if you are watching TV, make sure that you are not watching lustful images. When you are on the net, make sure you are not looking at ****.
By keeping from sin, you are giving God glory, no matter what you do.
Hope this helps.