Particularly if you are not particularly active, walking can be a good way to get your body moving and build your overall physical strength. Gradually increase your speed as well as the distance or length of time you walk.  Aim to walk at least 30 minutes a day every day, in addition to other physical activities. Escalating your walking to running can cause a greater reduction in ferritin levels. Warm up your body before any exercise, including something as low-impact as walking. Gentle, dynamic stretching before walking will help prepare your body. Working out with weights not only increases your overall muscle strength, new research suggests that it can reduce your ferritin levels. Try doing at least 40 minutes of strength training 3 times a week, along with your regular exercise routine.  You may want to start with resistance training if you have a hard time with aerobic exercises, such as walking or running. If you're new to weight training, you might want to start out with a trainer or experienced lifter so they can check your form and make sure you have proper form and that you're using equipment correctly. Intense exercise has the greatest effect on ferritin levels. This means going beyond regular, moderate exercise. To decrease ferritin levels, you need to engage in intense, prolonged training. Talk to your doctor about what types of training may be right for you, and to get recommendations for programs or professionals in your area that can help get you started.  If you don't have a lot of time to exercise, interval training can be a good way to increase the intensity of your workouts. High-intensity interval training can burn a significant amount of calories in a short period of time, as well as potentially reducing your ferritin levels. Athletes with normal ferritin levels have a high likelihood of developing an iron deficiency as a result of intense training. If you've just started an exercise regimen, it may take months or even years before it starts to affect your ferritin levels to any...

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Write a summary of the previous text in Indonesian:
Mulailah berjalan kaki secara rutin. Lakukan latihan ketahanan. Tingkatkan intensitas dan durasi olahraga. Bersabarlah.