Are you suggesting that if I don't drop three of those, I won't succeed in any of them? That worries me a bit, because the job part takes up LOTS and LOTS of time, far more than the other three combined.
1. Goal: Keeping fit. Invest 30 minutes each morning to that goal, which leaves 3.
2. Goal: Your job. Again, this is timeboxed until 5 pm, so do whatever it takes. Which leaves 2.
3. Goal: Play guitar. Not it gets tricky, because you could do both. But I think, again, timebox them. Monday through Friday you concentrate on your guitar, which leaves only 1.
4. Goal: Udacity. Now that you can do on the weekend. You will probably still play some guitar (I know I do), but thats not "learning", but playing (which is also important).
I think if everything is timeboxed and planned, I at least don't have problems keeping up, because I don't feel overwhelmed.
You'll know if you have so many that it's holding you back, and paralyzing you.
If it's not a problem, if you're able to progress on all of them, then congrats! No need to change anything because of a silly blog post. ☺