Squats! Every single day! There are thousands of different leg exercises you could do and it's good for you to mix it up, just google it. And don't forget to stretch out, especially your hip flexors
Place a soccer ball sized ball in between our calves. Then use something to put under the front of your feet (I used small red bricks) so you are on your heals. Then do 5-10 squats.
No stirrups, bareback etc