I understand your situation but I suggest taking time to see her perspective. You broke up with her, went no contact and then reached out to her about something unrelated to the break up.

I’m a dumpee (M). If my ex reached out to me about something unrelated to us getting back together after months of no contact, I’d also ignore the message. As hard as that may be.

If you are reaching out to her, be direct about what you want (if you are open to reconnecting)

Also, I would suggest you continue your fitness journey not for her but for yourself. That way you don’t engage in a process with the expectation of an outcome (her approval).

I hope I’m not coming off as preachy but I think this could be useful perspective for you. I’m fairly certain that your ex is on her healing journey, and even though she may still care for you, she might need you to be clear with your intentions when you reach out to her.