Welcome to TE I'm really glad you're out riding! As far as advice, I'm not much help. I do have a dear friend with Lupas and she really has to be careful about overdoing anything or she has a big setback. So, be careful! She was never active though.

I would think maybe walking days and rest days would be important for you. You will gradually improve. Be Patient! You will get there.

Keep in mind, I'm no expert on the subject. I bet you will get some great advice from the ladies that really do know what they are talking about!