I get asked all the time about how to tone up your arms, for good, and honestly it's just consistency in weight training! Of course your diet is #1, but weightlifting 3-5x per week for 20m can be a true game changer.
Here's a fast circuit you can do at home. Repeat the circuit 2-3x and using up to 8lbs depending on your fitness level. Keep those abs tight + stay focused on control and form!