As young and energized as you are right now, I suspect you are thinking this idea is "doable." However, energized or not, you will need some "down-time" to re-energize. I believe having two careers will have you burned out by the time you are 30.
However. . . I have some ideas. Some people have a volunteer interest that they commit a lot of time to. Some have part-time jobs. The challenge with either of these ideas would be in establishing yourself as a professional in that field. Another idea is to find the intersection of these two career paths.
For example, specializing in animal therapy with youngsters. I do not know enough about it to direct you. The things I have seen are more at a volunteer level. There are people who take dogs to visit the elderly in nursing homes, or children in hospitals. There may be special programs at zoos or places like SeaWorld, I don't know. There is a program here that uses horses. Please see this link: http://thesaddlelightcenter.com/
Hopefully you find the answer to how you want to proceed! Wishing you the best!