There are situations in which arthritis cannot be prevented. This is especially true when arthritis develops has a genetic factor. However, taking care of your joints over a lifetime can either prevent osteoarthritis or at least slowdown disease progression of any type of arthritis, including rheumatoid arthritis.
For example, it is critical to maintaining a healthy weight because every 10 pounds of excess weight increases the force on knee joints by 30-60 pounds. Some of the positive behaviors to protect joints include getting regular exercise that does not create a high impact on the joints, following a well-balanced diet, lifting heaving items with a proper posture (protects the spine and hip/knee joints), carrying items held close to the body (protects wrists) and taking regular breaks from repetitive tasks. Always stay aware of the stress you are putting on joints no matter what you are doing.