Take on one at a time. It's hard enough to achieve one goal without striving for multiple goals at the same time. If you want to become healthier this year, you may be taking on too much if you try to give up smoking cold turkey, start exercising every day and completely change your diet all at the same time.
Start small. If your resolution is a large goal, break that goal down into smaller pieces. For example, if your goal is to lose weight this year, set smaller goals you can more easily keep, such as aiming for three days of exercise per week by a certain date. Once you've reached that goal, set a new one - and keep going until your overall resolution is attained.
Share with others. Breaking your resolution is easy when no one else is around to hold you accountable. Tell your friends and family about your goals. Doing so will ensure that you have someone to share your struggles and successes and someone who can help kick you in gear if you need it. Asking for support isn't a sign of weakness - it's a sign you are serious about meeting your goals.
Don't give up. You might not reach your goal right away. Or you might give in and eat a brownie instead of sticking to your diet. If you get off track, forgive yourself, get back on the road, and stick to your plan. Minor detours along the way to your goal should be expected and are completely normal. What's important is getting back up and continuing on your path to success.
Write it down. It's easy to say you want to lose weight but more difficult to actually do it. Plot out a step-by-step plan of how you will attain your goal, including realistic target dates for completion. If you feel like the goal is becoming impossible to achieve, go back to your plan and revise it to meet your needs and still reach a comparable goal.