Keeping in shape and dieting always makes it into the top five and unfortunately are often the first resolutions to be broken. Often this is because specific goals that are set are unrealistic and do not include a commitment to make a fundamental change within.
My best advice is make small but incremental improvements regularly. Minor changes in eating habits and regular exercise will provide great long term results.
Rewards such as more energy, better sleep patterns, improved self esteem lowered risk to disease are all waiting to be claimed. This time next year you could be in a very different place ....Good luck