Plan a fitness challenge with friends that won't injure anyone

Plan a fitness challenge with friends.

Idea: [steps / workouts / streak]
Length: [days]
Abilities: [mixed / similar]
Prize: [optional bragging]

Ask me up to 3 short questions first if anything important is missing. Wait for my answers.

Then:
1. Clear rules including rest days.
2. Tracking method.
3. Opt-out / modify rules for injury or illness.
4. Reminder: anyone with a condition should check with a GP; sharp pain → stop.

Only use what I've told you, leave blanks for anything I haven't given, and don't invent diagnoses, doses, calorie targets or treatment plans. This is help with preparation, planning and wording, not medical, diet or treatment advice; check the NHS website, speak to a pharmacist, or contact NHS 111; call 999 if it feels like an emergency. UK English.

Stay in this ChatGPT chat. Do not turn on apps or connectors, and do not use memory from another chat.