Your natal chart is a snapshot of the planets and other bodies and positions in the Zodiac at the moment you were born from the location you were born at. Each part of your chart shows different parts of your personality and life, and you can find your goals with your Midheaven.
Also called the Zenith or Medium Coeli (or MC for short), the Midheaven is the highest part of your chart, therefore connecting with what you aspire for in life. It's what you look up to being, so it shows the goals you have in life.
Midheaven and Career
Since the Midheaven is what you aspire for and your goals, it naturally links to your professional life and career. This is NOT the same as your job (which is the 6th house) or how you best make money (which is the 2nd house). Astrology differentiates between them!
Usually, whatever career you end up choosing, you'll find it directly ties into your Midheaven somehow. It may be ruled by the sign your Midheaven falls in, planets in the 10th house (connecting to the Midheaven), or the natural planetary ruler of your Midheaven sign.
Goals that aren't professional and your Midheaven:
Now, here's the thing - not everyone has major goals that are professional in nature. Some people never want a career, and their goals are not related to work. Your aspirations may be related to family, philanthropy, heck even simply being a beach bum! (haha)
This is usually still shown through your Midheaven. They're still goals, just not professional ones. In these cases, you'll usually see the Moon/Cancer (ruling family), Uranus/Aquarius (ruling charity, but also the unconventional), or Neptune/Pisces (for the beach bum!) involved. Bottom line, you're going to see it reflected with your Midheaven somehow, so don't automatically assume that it's career and career only. It's not!
When can I achieve my goals?
You tend to make progress when your Midheaven is being activated by transit (moving) planets. The biggest times usually come when you have a transit or progressed planet, or a new/full moon/eclipse conjunct (aligned with) your Midheaven. You can see all of your hard, smart work pay off and experience some success or positive developments then. BUT only if you've been working smart and doing things the right way! Otherwise, these are times you can experience major setbacks.
Transit and progressed planets, and new/full moons/eclipses that are sextile or trine your Midheaven can bring positive periods for you without the worry about setbacks. These are the beneficial aspects, so you don't have to deal with the challenges as much. But they're not as strong as the conjunction to the Midheaven.
Transit and progressed planets, and new/full moons/eclipses that square your Midheaven can bring the biggest challenges to progress. You likely have some blocks that you need to work through, and you still may not make progress, but can at least stave off the big setbacks or failures.
Suggested Reading: The Empty Career Houses: Empty 2nd, 6th & 10th House in Astrology