Using a mat, thick towel, or carpeted surface is more comfortable than lying on a hard, bare floor.  To broaden your workout and engage your entire core, you could also do crunches on a stability ball.  For more resistance, you can try doing crunches on a declined exercise bench. Your knees and feet should be about hip-width apart. Position your feet so your heels are about 12 to 18 in (30 to 46 cm) from your tailbone.
एक एक्सर्साइज़ मैट पर अपनी पीठ के बल लेट जाएँ: अपने घुटनों को मोड़ ले, ताकि आपके पैर जमीन पर एकदम सीधे रहें: