Setting goals is one thing, but achieving them is another. So it is important to set realistic goals. Do not ask too much of yourself by setting the bar too high, this can actually demotivate you and make it harder to achieve your goals. So keep your goals manageable, so you can achieve your personal goal step by step.
Maybe your ambition is to work out every day this winter. If you already work out four or five times a week, this is a realistic goal. But if you don't work out or only work out once a week, then working out every day is an unrealistic goal to achieve in one go. What you can do is to set sub-goals for yourself. First, try to work out at least twice a week for the next month. Will you be able to do that? Then next month you can set the goal to work out 3 days a week. And so you can build up to 4 or 5 days a week or maybe even every day.