Some lessons I've learned while weight training, especially in the last few months:
- The back and legs have the largest largest muscle groups in the body, and working them out (even for a short duration) not only strengthens these muscles, but also affects the body's overall physiology. More experienced weight trainers refer to this effect as the GH boost. Lesson: If one can work out for only two days a week, it should be for the back and legs, instead of the chest, biceps, shoulders, etc. [but one should work out more often to include them as well]
- If the body is excessively sore after working out, it helps to feed on some carbs. Carbs do aid in recovery, and can help get back to the gym the next day. Of course, it helps if the carbs are not made of refined sugars :-)
- Compound exercises work out more muscle groups than isolation exercises, and a lot of them end up hitting the core muscles. Again, if stuck for time, compound exercises are the way to go.