The tail end of Three Lakes Trail will dump straight into the Alta Vista Trail. Alta Vista immediately has a hill that gets steeper in grade as you go. It's not the longest stretch of uphill, but it's enough to get you sweating! The vista at the top is breathtaking and so worth the climb.
From there out, it's all downhill, leading to the Oakwood Trail. On the way down, keep your eyes out for some mushrooms. There are lots that grow among all the oak trees in the shadier spots.