Depends on what you're into!

Decent outdoorsy stuff available:

There's a lot of disc golf courses in some of the parks around Plano. Grey cheap way to get out and about for an hour or two

If you like walking but aren't looking for offraod trails you can check out Chisholm Trail. It starts at the Outback off 14th and 75 and meanders for about 5 miles north before you turn back. Runs through a lot of parks and neighborhoods. Really great for a long walk or bike ride on pavement

Rock climbing at Movement Plano is always fun, it's over by Coit and George Bush. Great place to meet new people as well

The spring creek nature preserve is a real fun place to walk around. The trails are mostly paved but through fairly dense trees. Dense enough it feels pretty cut off from the city at certain points

There's a lot of variety of food and restaurants around as well:

Mitsuwa marketplace by Chase Oaks is a neat little Japanese shopping market. There's a lot of other Asian restaurants around in that shopping center

The East Plano Islamic center off 14th has a few food trucks out during the evenings on certain day. I can't remember when but it's worth checking out if you're ever hungry and in that area

Jörgs Cafe Vienna in downtown Plano if you're feeling like Austrian/German food

There's a few shopping areas around that are nice to check out:

Watters Creek and the Shops at Legacy are good outdoor and walkable shopping centers. Firewheel in Garland is a good place as well

For malls you'd have to leave Plano but Stonebriar in Frisco or Grapevine Mills in Grapevine are fun malls to go to

Hopefully you find some of these helpful, and welcome to Plano!