I'm at a point where I don't know what the next step in my workout/diet plan should be. Here is my situation, and my goals. I would appreciate advice on where I should go from here:

i am male, 20 years old, 5 feet 10 inches, and in college. In high school, I ran track (mid distance), ate whatever I felt like, did little to no strength training. I was consistently 155-160 pounds. When I got to college, my eating habits didn't change much-- but if they did they got a little worse. I also stopped running regularly. Sure I did intermurals and what not, but I was not nearly as active as I was in high school (running basically every day). By the begining of the second semester of my second year (this past january) I was 185lbs and when I participated in physical activity I could feel how out of shape I was.

So, for the last 4 months i've been on a diet (2000 to 2500 calories a day, with very little fat, no sweets or soft drinks, and mostly chicken and fish for meat), gotten back to running (2-3 miles a day again), and for the first time in my life started strength training (alternating push, pull, and legs at the gym 4 or 5 days every week). I've made progress in all areas. I can do 3 miles no problem again and my times are back where they were in high school. My weight is down to about 163 lbs, and I am lifting much more weight at the gym than when I started (i was pretty pathetic when I started!). There is also a noticeable change in my physique. For the first time I have some muscle tone in my arms, and abs, and to a lesser extent my chest.

Unfortunately, i'm kind of hitting a wall in all areas. Running I would expect-- i'm pretty much back to the times I was running in high school, and I don't expect to do much better. Really, i'm running just for the sake of cardiovascular health anyway, and that is a key point: my ultimate goal is to do what is generally healthy, not to push myself to extremes in any one direction.

I don't want to be a marathon runner or a body builder; ultimately I just want to be healthy, get myself into good habits, and reduce risk of partially preventable diseases. The one area i'd like to see more improvment, however, is my strength. I've been stuck on the same weights for a while now, and i've been told by lots of people I won't put on any muscle mass unless I turn my diet around, and start eating for a calorie surplus every day. Lots of people suggest phases: weight gain for strength and muscle mass, then go back to dieting to lose the fat gained during the bulking phase while hopefully preserving the muscle.

There are lots of websites that suggest how to bulk up, but I just wonder: is this whole phase thing healthy? They all focus on making you stronger, which I want, but I want to do it in a healthy manner. I know gaining, losing, gaining, losing weight in general is considered a bad thing. No one wants to yo-yo diet right? But that seems exactly what this is, except you add in the strength training so you gain in the form of mostly muscle. Does that negate the unhealthy effects of yo-yo dieting. Is having lots of extra muscle even good for you? Just because you are bigger and stronger doesn't mean you are healthier, does it? How many professional athletes have heart trouble later in life? Just wondering if anyone has specific info on the health effects of this kind of thing. I need to figure out where i'm taking my routines from here.

That was long.....So if I didn't put you to sleep, thanks for your time and advice!