Just west of the city of Fort Collins is Horsetooth Reservoir. This is a great scenic drive and offers paddle board rentals at the north end of the lake. Just past the reservoir is Horsetooth Rock hike which is an approximately 6 mile loop hike up to the overlook with great views of Fort Collins and the Rocky Mountain Range.
About a one hour drive west of Loveland is Estes Park and the entrance to Rocky Mountain National Park. Walking around the town of Estes Park is a great day trip, horseback trail rides are available through the YMCA of the Rocky's Jackson Stables, and multiple tours and trips are available into the Park. Please note that a reservation system is in place to enter Rocky Mountain National Park. Reservations fill up quickly, however you are able to enter the park every day after 3pm. Casual hikes in the park that can be done after 3pm include Bear Pond and Dream Lake (2 miles round trip). Sky Pond hike is another great option if you can get into the park earlies (about 9 miles round trip).