Here's a dilemma. Yoga, meditation, mindfulness training, blah, blah, blah, all rely on the notion of being present, as well as setting an intention. If you are setting an intention, you are thinking about the future. And if you are present, you are not. Quoting one of my teachers, "If you are present, who pays the light bill? -- and if the lights are on, is anyone home?"
Setting an intention means thinking forward in time. Being present means being here now. So, how do we manage both? Simply, we live backward in time!
Living backward in time means living in the now as if it were the future that you envision. A friend of mine calls this living "as if", instead of "what if"...and it's very effective.
Let's look at this very practically... Let's say that you want to lose 15 pounds. You know that to do this you need to eat more healthily, exercise regularly, learn something about nutrition, learn something about supplements, etc. Big job. So, you go on a diet. Great! You lose 15 pounds...but then you gain it back. Why? Because you approached the moment like a person who wanted to lose 15 pounds, not someone who was 15 pounds lighter, and therefore more healthy and the owner of a different lifestyle.