Martin, back to your opening topic, which, as so many on here do, got a bit hijacked. If you want to learn about being positive and staying that way, have a look along the 'self help' books in a good book shop. It may be an oldie, but Dale Carnegie's "How to Win Friends and Influence People" is still a very good book in suggesting effective ways in which to focus on what is positive about YOURSELF and how to project that to your advantage (without damaging other people).
A pal of mine gave that as a Christmas present to his friend's daughter, who's doing Media Studies at present, but isn't very focussed. She may decide not to focus on reading it, but it's a very easy-to-understand book and helps the reader to set sensible goals.
Don't set goals too far ahead, as some may not be able to be met if your life changes in the meantime. But, as is suggested, having SOME sort of goal or goals gives you something to measure your progress by.
Don't be afraid to change the goal or the time you've set to achieve it, if other things happen to affect it. For example, you might say, "I want to be doing XYZ in year 2010." But perhaps in the meantime, you meet someone who says, "Let's go backpacking for a year, Martin", and the goal won't be met by then if you accept. The thing is to decide if the backpacking experience would be appropriate at the time that's suggested, or if it sounds like something you really want to do, and then decide if you'll do it, or not. The goal to be reached by 2010 might then slip a year or two, but if it won't affect you in a negative way, there's no problem, is there? So you can be flexible with goals.
Some goals are reached more quickly than expected. So, you can decide to set a new one that follows on, or a completely different one - such as learning or doing something you've not tried before.
And, sometimes, you begin to realize that a particular goal is NOT going to be reached, ever. It might be because your circumstances have changed, and you can't attain what you hoped for, or you realize that you don't actually have any more interest in its' attainment. That is not a 'bad' thing, it's just a different outcome.
There's also another book to recommend to you, called "The Power of Positive Thinking", which has been used by thousands of people. You can probably borrow it from your library if you don't want to buy it, as I expect it's still available. Like the other book, it helps you to focus on what's helpful, and to discard what is not helpful, in everyday thinking and in your attitude towards your life.
Good luck, Martin!