To become an activewear brand, you will need to have knowledge of the apparel industry, fabric selection, and garment construction. You will also need to have a network of suppliers and manufacturers to source materials and production services.

Building an activewear brand involves several steps, and here are some essential steps you can take to get started:

1. Research the activewear market: Conduct market research to understand the current trends, consumer preferences, and competition in the activewear industry. This will help you identify gaps in the market and opportunities for innovation.

2. Identify your niche: Determine the specific market segment you want to target. Do you want to focus on yoga apparel or gym wear? Are you targeting a specific demographic like women, men, or children?

3. Create a business plan: Develop a comprehensive business plan that outlines your brand's vision, mission, and values. Include financial projections, marketing strategies, and product development plans.

4. Develop a brand identity: Your brand identity includes your brand name, logo, and overall image. Ensure that your brand identity reflects your target audience and stands out in the market.

5. Source materials and manufacturing: Select high-quality, performance-based materials that are suitable for activewear, such as moisture-wicking fabrics, stretch materials, and breathable materials. Select high-quality materials and reliable manufacturers to ensure your products meet your brand's quality standards.

6. Design your products: Create a unique product line that meets the needs and preferences of your target audience. Designing products that are both functional and stylish. Develop a unique and attractive design for your activewear products. Ensure that the design is functional and meets the needs of your target audience.

7. Find manufacturers: Locate reliable and skilled manufacturers that can produce your activewear products. This may involve working with overseas factories or domestic suppliers. Sharing them your ideas for the design or tech-pack and get samples/orders.

8. Set up an online store: Establish an online store to sell your products. Optimize your store for search engines, and use social media platforms to market your brand.

9. Launch your brand: Host a launch event or promotion to introduce your brand to your target audience. Use the opportunity to generate buzz and attract customers.

10. Monitor and adapt: Keep track of your brand's performance and make necessary adjustments to your products, marketing strategies, or business plan to ensure your brand's success.

Building an activewear brand requires a lot of hard work, patience, and dedication. However, by following these steps, you can create a successful activewear brand that stands out in the market. More details you also can contact with Sansan sports team with thier professional person who will help to creat and get that starting.