I've long lost count of the number of goals I've set and achieved, or failed to achieve. But I have found that in order to achieve a really long-term 'I really want to achieve this' type goal we need to set up the necessary habit which will allow us to keep going.
Bearing in mind that it takes three weeks to establish a habit, the proviso being that not one day is missed in that three weeks (otherwise we start again) it is in our interest to establish the habit or habits which will enable us to go about our daily living in such a way that what we are doing is a part of our daily routine.
For example, if you want to become a writer you must write every day. It might be for, say, thirty minutes. Do this for three weeks solid and it becomes easy to carry on. if you want to become a musician you must practice every day until it becomes a habit. Once the habit is thoroughly established, then you can miss the odd day or so. The established habit will draw you easily back.
The same applies to giving up, say, smoking. The hard yards are the first three weeks. No smokes for three weeks - habit established. You drop back. No worries. Just keep going as a non-smoker.
Certain habits are essential if you are to succeed in any major undertaking. You'll know what these need to be. Then, as old Winston Churchill said, "Never, never, never, never, give up."
Feel motivated? ...Go form that good habit so you can realize that long-term dream you hold.