Design an Interval Training Session for Speed

You want to get faster but throwing in random hard efforts isn't a plan. Give it your current 5K time, target distance, today's time slot, and whether you're on track, road or treadmill, and this designs a full interval session, warm-up, main set, cool-down, with the purpose of each part explained so you know why you're hurting. One workout, built for today.

<context>
I am an intermediate runner with a current 5K time of [current 5K time] and I want to improve my speed over [target distance]. I have [available time, e.g. 45 minutes] for today's workout and access to [track / road / treadmill].
</context>

<task>
**Design a structured interval training session** tailored to my current fitness and goal. Include warm-up, main set, and cool-down. Explain the purpose of each interval block.
</task>

<output_format>
- Warm-up routine (time and pace)
- Main interval set with reps, distances, target paces, and recovery periods
- Cool-down routine
- Perceived effort targets (RPE scale)
- What adaptation this session builds
</output_format>