Here's a sample first-day gym routine boy and girl:

 Warm-up (5-10 minutes)

1. Light cardio: treadmill, bike, or elliptical

2. Dynamic stretching: leg swings, arm circles, hip circles

Upper Body (30-40 minutes)

1. Bench Press: 3 sets of 8-12 reps

2. Lat Pulldowns: 3 sets of 10-15 reps

3. Bicep Curls: 3 sets of 12-15 reps

4. Tricep Dips: 3 sets of 12-15 reps

Lower Body (30-40 minutes)

1. Squats: 3 sets of 8-12 reps

2. Leg Press: 3 sets of 10-12 reps

3. Lunges: 3 sets of 10-12 reps (per leg)

4. Leg Extensions: 3 sets of 12-15 reps

Core (10-20 minutes)

1. Plank: 3 sets of 30-60 seconds

2. Russian Twists: 3 sets of 10-12 reps

3. Leg Raises: 3 sets of 10-12 reps

Cool-down (5-10 minutes)

1. Static stretching: focus on major muscle groups

Tips

1. Start with lighter weights and focus on proper form.

2. Rest for 60-90 seconds between sets.

3. Adjust the routine based on your fitness goals and preferences.

4. Consult with a personal trainer or gym staff if needed.

Remember, consistency and patience are key. Stick to your routine and make adjustments as you progress.