Make it all one activity for 30 minutes, or split it up into multiple sessions of one or more activities (like walking, swimming, cycling, dancing ... ). As long as you get 30 minutes total!
Do: for 30 minutes
Any aerobic/cardio activity at whatever level works for you. Some examples are walking, running, cycling, skating, swimming, and dancing. Also sports such as tennis, basketball, soccer, and hockey. Anything that gets your heart and lungs pumping.