What should I major in?

You have a very good goal here.

Ask yourself this question: Is the need for your organization -- the void in students' lives you're hoping to fill -- primarily one of practitioner skill, or primarily one of students' access and society's willingness to meet their needs?

Put another way: Suppose you were the Gates Foundation and you wanted to fund this cause right now. Would you look for an executive director (ED) who was an expert licensed mental health practitioner with the skills to give a unique kind of care, and to teach others to do that? Or would you look for an ED with talents in persuasion and political advocacy, who could hire the right licensed practitioners?

Either way the Gates Foundation would insist on an ED with a track record in development (which means "fundraising" in the nonprofit world).

If you believe your org will give a unique kind of care, focus your college education on learning to give the sort of care you believe in. Think about whether it's primarily focused on psychological or social issues. That will help you decide from among psychiatry, psychology, and social work as your focus. Those fields have good support systems in university, as others here have mentioned.

On the other hand, if you believe your org's uniqueness is to get access to this kind of care, you should consider studying history, politics, and economics. As the ED you'll be a politician and activist more than you'll be a care deliverer.

In either case you'll need a good background in the mechanics of business. Do not neglect this part of your studies. In caregiving work, the difference between organizational success and failure is often the ability to deal with payers, landlords, and suppliers, and your accounts.

Done well, the practice of mental health is both personal care and advocacy. A caregiver who finds herself seeing lots of people with opiate addiction shows up at her legislator's office and pounds her fist on the desk demanding change, for example. You'll do well to try to learn both the political and caregiving disciplines. And, if you want to direct an org, you'll need topnotch business skills.

It's a lot of stuff to learn! But you can do it.

As you're learning to do it, consider working (as an intern , then as a staff person) in an existing org that delivers your sort of services. You'll learn a lot of practical stuff that you could never learn in school. If there's an org you admire, ask the ED for 20 minutes, tell him what you want to do, ask for advice, and offer to work for him. Also, ask for the names of other people you could talk to.

For introductions to good orgs, ask your local guidance counselors, youth-center workers, and ministers for referrals.

Starting/running a non-profit requires a different skill set than the actual provision of mental health and educational services...

While I am supportive of the other responses to your question that have been posted so far (especially discussion with teachers and guidance counselors), I would also recommend that you look at business course work as well. There are several universities which offer masters level programs in nonprofit leadership. Do a google search to find them! Another suggestion would be a masters level degree in public administration.

Licensed Certified Social Worker - Clinical

Licensed Certified Social Worker - Clinical (LCSW-C) If you wish to hold the title of Licensed Certified Social Worker - Clinical (LCSW-C)

Licensed Certified Social Worker to designate those who have completed a master's level education and 3000 hours of supervised work. In this case, an extra C (for Clinical) is added at the end (i.e., LCSW-C) to indicate clinical or mental health practice (instead of management, or other nonclinical work).

Masters Degree Graduate in Social Work with a minor in psychology

Some social workers with extra clinical work certification also have the BCD at the end of the LCSW, which stands for Board Certified Diplomate.

The C allows for you to practice as a clinician therapist you are able to write scripts and bill the federal govt. value options for medicare and medicaid.

The average beginner in this position makes around $49K, but folks who have been around for five to 10 years see a markedly higher median salary of $54K. Licensed Clinical Social Workers bring in $59K.

Program management and ownership of therapeutic programming makes around $80K up to $100K.

Create a practice design and a business plan for your social work private practice. What kind of clients do you want to help?

develop a thorough business plan and marketing plan for your business

Exemption Requirements - 501(c)(3) Organizations - IRS.gov
https://www.irs.gov/.../Exemption-Requirements...
Internal Revenue Service
To be tax-exempt under section 501(c)(3) of the Internal Revenue Code, an organization must be organized and operated exclusively for exempt purposes set ...

and utilize research from

The Social Worker's Path to Private Practice - Dr. Lynn K. Jones
www.lynnkjones.com/privatepractice/
The Social Worker's Path to Private Practice – How You Can Get From Here to There ... She has written four books about the business of being a therapist and coach ... advises students who are planning to develop a private therapy practice

good luck on your new journey start now while your young and be fully loaded and ready for action now it will put you above the rest so you may prosper and enjoy your life

If you want to run your own enterprise, major in business and then take a couple of classes in the topic your enterprise will deal with.