What to do when injured?

I have been fighting with a bad knee for a couple of weeks and it has really hampered my workout schedule.

For a week now my top priority has been to strengthen my knee by riding a stationary bike with low intensity

I can still do upper boduy weights and have worked that a lot but still I know that my stick legs will be worse soon so I need to get the intensity up on the bike.

What do you do to work arounf injuries and still train?