The trailhead for Mills Lake is Glacier Gorge.  The lake is about 2.7 miles from the Glacier Gorge trailhead.  It takes you past a couple of additional can’t miss sites (some of which you literally can’t miss because they are clearly visible).  The biggest two are Alberta Falls and Glacier Falls.

Mills Lake was amazing for its solitude.  There were a few hikers back there, but they were all quiet and just enjoying the sights.  The hike out to Mills Lake is not easy, but it is not terribly strenuous.  There is some altitude gain (I believe a little less than 1,000 feet), but not enough to worry too much about and the lake itself is a little below 10,000 feet so you should be okay.

The views on the trail to Mills Lake are simply amazing.  You follow a gorge cut by a glacier (hence Glacier Gorge trailhead) and it winds through trees, across rocks and around the edge of cliffs.  Much of the trail also follows a river so the sound of running water is always with you.  Because you are pretty high at points you can see off in the valley with Estes Park and you can see some of the peaks including Flattop Mountain.

All in all, this is a great medium hike with views and scenery that can’t be beat.