Hansaji of The Yoga Institute says that instead of trying to practise yoga for a n hour or so , try to bring in yoga practises through out your day. Like, when ever you need to bend down try squating in Utkatasana. Before beginning any new task try breath awareness for a minute. If you have been sitting for a while, get up and do some konasana or a hand to toe or padahastasana.
So, you can do practises through out the day and feel energised all day long. Also, you will not have to keep a speacial time slot for yoga !! This way you do not miss out on your practises.