Please remember doxies will not be marathoners and even walking a mile may be tough at first. Stick to short walks and increase a little each day. Play time should be filled with fun and love and should be a bonding time for you and your doxie. You never know what can happen. Having a doxie is like having a toddler.
Most adoptees go through something called abandonment syndrome.
Because they are such a loyal and loving breed they will want to bond with you and be with you at all times. In short, they are afraid of being left yet again. Be understanding and loving. Once the comfort level goes up, the need to act like Velcro will go down. Love Doxies want and need love, lots of love.