BTW: I also agree with Bettye's answer as you may have multiple "careers" over your working lifetime.
Actually I was 40 years old when I became a Licensed Professional Counselor. I was a college administrator who was given the opportunity to return to college to complete my graduate degree join the faculty as a counselor/professor. There was a dearth of Counseling professionals to accommodate our 20k student population, so I welcomed the challenge. It has proven to be a very rewarding career choice!
My software engineering career education "officially" started in High School with a couple of programming classes. However, my interest in computers began back in my elementary school days where the school I attended had a program where all 4th and 5th grade students got a computer to take home and we were required to do our homework on them. This was in the early days of the public internet and everything about computers, computer games, the internet interested me. I always wanted to know how they worked and how the games or software I used was built. In high school I finally got that start and then went into studying computer science as my college major.
I came out of college when the software industry was still recovering from the .com bust of the early 2000's. I got my first real software job working a very small local startup that was focused on revolutionizing the propane tank exchange industry. After a couple of years in that role and not a ton of forward momentum, I made a jump to larger more establish software specific company really began growing my skillset and experience from there.
In looking back the key for me was getting a foot in the door somewhere and then always looking at where I was headed and whether that was the direction I wanted to be going. If it wasn't, then I'd look to make a change to what did align with my goals.
My very first job experience was as a freshman in high school as a Soccer Referee, which I continued throughout my high school and college career. Looking back on that experience, the biggest advantages of working throughout high school was that it allowed me to supplement my SAT scores & grades with tangible work experience on my college applications.
Transitioning into my professional career, I completed my first internship at the age of 22, at a telecommunications company in Medellín, Colombia. This was an excellent introduction into the professional workforce, in addition to the abroad experience which employers also value. (If you're currently in college and interested in abroad/exchange opportunities, see if your campus has an AIESEC chapter which offers opportunities to work abroad over the summer).
If I were to do it all over again, I would have more aggressively searched to complete a professional internship over the summer after my sophomore and junior years. I can't stress enough how important it is to find any summer internship opportunities that you can highlight on your resume and showcase to employers as you're graduating from college.
After returning from my abroad experience, I decided to transition into the tech industry and landed a full-time position at the age of 24.
To conclude with some reflections/advice, it's never too early to gain work/volunteer experience that, in addition to being an enriching personal experience, can be used to strengthen your prospects for landing a career, or getting into college.
I began my career at age 16. I knew by then I wanted to work in the computer field, ideally programming, so I got part time work as an assistant to an IT consultant. He had me do all the gross jobs (like getting down into dusty crawl crawl spaces to pull cables) but he also taught me a lot about computer systems along the way as well. In college I was able to reference that experience to get an IT job on campus as well, so I was studying computer science theory, and in between helping build networks and servers in a very practical way.
If you can do it, it's great to find entry level work in the field you're interested, even if you're still in school. You might find that the career isn't what you imagined it to be as well, and be able to change direction before investing too much of your education in a certain direction.