I love aspects mathematics, especially those which when I can apply it to real situations.
If you're a programmer looking for calculus applications, I'd have to say computer graphics, particularly physics simulation. Of course, that requires you to learn computer graphics if you don't know it already and a little physics. There aren't that many actual programming jobs where you get to apply calculus, but this is definitely a place where you can put it to work from a hobby point of view if you know how. So, for example, I wrote a little program recently that simulates a ball the hits the ground and bounces, using 0.5gt^2, which is a somewhat trivial application of calculus to physics. More generally, you could tell the computer what the acceleration or velocity is and have it display the ball's motion according to that. That's one of the big applications of integration.
However, when mathematics becomes so abstract like aspects of precalculus/calculus it becomes faint for me, at times.
If you think that's abstract, you ain't seen nothing. I thought I had reached the peak of abstraction when I took my first topology class, but I hadn't seen nothing at that point, either.
How do you keep it fresh, interesting and rewarding? I am a computer science major and I want mathematics to be my best friend. In short, I am just wondering what tips you can give me to keep mathematics interesting.
The way I keep it interesting is to try to visualize a lot of it, but it can be challenging to do that, if your teachers don't explain it that way. This might give you some hints:
http://www.maa.org/sites/default/files/pdf/devlin/LockhartsLament.pdf
Not all of it is going to be thrilling, though, I think. Stuff like trig integrals just isn't the most riveting thing in the world, I think. I think the "application" of that stuff, if you want to call it that, is mostly just so that you get more practice applying the concepts in different settings. You may never use some weird trig integral, but learning how to do it could breed a little more familiarity with integration by substitution and other techniques. I think if you get though your calculus class and all you remember is what a derivative is, what an integral is, enough to do some basic examples and apply the concepts, plus the fundamental theorem of calculus, then that's 90% of the point of the class right there, for most people. You'll have a new way of looking at the world. The most useful part of it is probably just the basic concepts. But if you didn't spend some time practicing with it, doing problems, it wouldn't sink in as well.