healthy, nonharming activities that you can think of from The Dialectical Behavior Therapy Skills Workbook by Matthew McKay,

"healthy, nonharming activities that you can think of:
Instead of hurting yourself, hold an ice cube in one hand and squeeze it. The sensation from the cold ice is numbing and very distracting.

Write on yourself with a red felt-tip marker instead of cutting. Draw exactly where you would cut. Use red paint or nail polish to make it look like you’re bleeding. Then draw stitches with a black marker. If you need to make it even more distracting, squeeze an ice cube in the other hand at the same time.

Snap a rubber band on your wrist each time you feel like hurting yourself. This is very painful, but it causes less permanent damage than cutting, burning, or mutilating yourself.

Dig your fingernails into your arm without breaking the skin.

Draw faces of people you hate on balloons and then pop...

Lucy often cut herself when she felt upset or angry. She had dozens of scars on her wrists and forearms. She wore long-sleeve shirts even in the hot summer because she was embarrassed when other people saw what she had done to herself. But after getting some ideas from this workbook, she made a distraction plan. So the next time she got angry with herself and felt like cutting, she looked at her plan for alternative actions. She had written down the idea of drawing on herself with a red marker. She drew a line exactly where she would have cut herself. She even used red paint to make it look like she was bleeding. She carried the mark on her arm for the rest of the day to remind herself how sad and overwhelmed she felt. But then, before she went to sleep, she was able to erase the “scar”..."

The Dialectical Behavior Therapy Skills Workbook: Practical DBT Exercises for Learning Mindfulness, Interpersonal Effectiveness, Emotion Regulation, and Distress Tolerance
by Matthew McKay,