A wise client once told me about an approach that worked for her: 15 minutes at a time of the task at hand. It is easier to think “I can do 15 minutes of this” than to think about having to complete a whole project. Some goals are not time limited, like learning a language or starting an exercise program, and can be achieved by setting aside 15 minutes a day. Other goals that do have a specific timeline, like needing to get the house cleaned before the company comes tonight, can be broken down into 15 minute chunks with short periods of more enjoyable activities between them. Clean for 15 minutes and then get up and stretch, or pet the dog, or go for a quick walk, or dance to one song, or have a cup of tea before the next 15 minutes of cleaning. Set a timer if you find that helpful.
If the 15 minute approach seems too regimented for you, change it to fit your personality. If we take the goal of 'clean the house before company comes', perhaps one room at time, or one task at a time (sweeping or dusting) with breaks between will work better for you. Take a moment to celebrate the completion of each small goal. Experiment with other ways of segmenting larger goals into less intimidating chunks. If you create restorative breaks between segments of work you can often avoid that "uh oh, I overdid it” syndrome the next day.
Breaking goals down into manageable pieces also gives us the opportunity to ask ourselves whether doing this get me closer to where I want to go. At every step we can asses our direction, celebrate our successes, learn from our errors, and make adjustments if needed.