Leaders sometimes spend so much time thinking about the things they could have done that they forget the power they have to change things in the present. It's easy to get stuck in a mode where you replay past events or make up future possibilities but that never affects your present results.
Spending more time consciously working on the present is an effective way to improve your leadership skills. If you start today by telling yourself that you will work on something that actually exists right now in the present you will suddenly have greater command of your destiny and the ability to change whatever is happening.
Try taking action today; find something in the past or future that you wish would change and re-focus it in the present. Ask yourself what you can do right now to affect something in your workplace right now. Taking action in the present helps you take your mind off all the things you can't control and focuses your energy on the things you can change.