The hot shower or "heat before stretching" as always worked for me. That is, stretching is much easier, effective and doable once the muscle groups to be stretched are warm. This can occur in many ways including exercise, 15 minutes in a hot tub, heat lamps, massage, etc. As mentioned above stretching is designed to elongate muscle fibers.

Warm-up before activity typically should have a different goal. It should be aimed at preparing the muscles for use in specific activities. If one "stretches" as a warm up it will provide a very inefficient way of warming up. Even ballistic stretching (this is the old bouncing kind of stretch my gym teachers in high school made the entire class endure) is not all that effective, and one runs of risk of injury from tearing muscle fibers in non-productive ways. Static stretching (holding stretches instead of bouncing) is even a less effective way to warm up.