Well, I am a singer as well as a pianist; on top of that I am deciding to actually dedicate some real time and energy to composition and improvising as well. Where do I begin ?
I have actually been in huge angst over all of this before. I felt very much like I definitely *had* to choose between instruments ... and year after anxious year, I simply could not make a choice (or if I made a choice for awhile, I couldn't stick with it forever). This all actually made me sick, really sick, and I had to formally step back from everything that I possibly could step back from and do a bit of soul searching on my own (without outside influence). This step back lasted for about a year and a half until I slowly started finding my way again.
I will tell you what, time constraints are definitely something to be considered ! Well, it just so happened that during the time that I was soul searching on my own, I found this forum and started passionately (

) reading Bernhard

. He has posted information on how to get organized in one's life. Well, I still have a ways to go, of course, as there is always room for more oganization, but this has helped me tremendously in getting things done.
At first I had to just learn the system of organizing my time. So, before I had as many activiities as I have now, I learned how to juggle the batons that I had going with the system of organization I was learning. As I got better at that, I guess I started feeling like I could add more and more things in. I do still get overwhelmed sometimes, but that tends to be most prevelent when I am not sticking to or using this system.
Anyway, I reached some kind of crisis after crisis until I finally realized that I was not going to be able to actually give up either instrument. When I finally accepted this about myself and about my life, I realized the need to continue to consciously grow in several other areas. For one, I needed to not just organize my time but actually utilize it better (still working on that). One of the biggest changes that this brought about for me was to begin mentally practicing as much as I could. Also, I started to actually type up my goals for each day. I finally started to be able to function !
Another thing I have realized is the importance of discerning how these instruments together can help me grapple with each one separately. I have always tried to relate them together when I can, but I am entering a new phase in actually utilizing specific things about one to help my progress with the other. I think this is essential. My goal became/is to be one person who plays more than one instrument vs. two people who each play one (that is often how it felt). It's gradually gone from that concept to actually drawing on the same source for everything that I do in life, and seeing the greater connection between it all. So, when I am teaching, I utlimately strive to see how it relates to my playing, singing, composing ... I am drawing everything from the same pool and expressing myself from the same "pool" through everything that I do. It is beginning to morph into everything being of the same essence or substance, or that it all becomes one. Okay, that may be a bit abstract ... sorry about that for now.
Psychologically, it has in the past been *very* difficult for me. I had often felt extremely torn within myself regarding all of this. However, I know that part of my survival as a musician in general depended actually, on having more than one form of expression. There is a lot to that particular aspect that I won't go into for now.
One of the great things about piano is that it actually encompasses most of the concepts of music and instrumentation right there in black and white. So, actually, knowing more about other instruments can be put to use with piano study, and knowing about the piano can be used in the study of other instruments. I kind of view the piano as some kind of awesome "desk" where a person can bring their entire musical selves and sit down at this magic desk and work it all out.
I will admit though, I have had to make a bit of a decision that most of my "life" will center around my musical goals. I don't have much of a social life other than being here on the forum, and I have occasionally made friends through the forum whom I will talk with online. Other than that, my social life is with my students and my colleagues in the musical work that I do.
So, prioritization, organization and knowledge/experience carryover. That's how it's done.