Activities are one of the mission types you can receive and they are quite simple to complete, they can be found in the mission menu, far right next to the completed tab. Unlike the other mission types, these won't have an official mission name, and won't be logged once they are completed. While playing you'll frequently receive/find an activity, so I wouldn't worry about not finding 30 of them!
You can check your
statistics by going into the menu
, and pressing
. In the mission tab you'll see how many activities you've have completed so far.
Here's a great list of activities and how to get them, the current list shows that you can get 21 activities in New Atlantis alone! - https://starfield.wiki.fextralife.com/ActivitiesThere are several ways you can get one, such as accepting to help an NCP/choosing a specific dialogue option, overhearing an NCP's conversation when you walk past, picking up certain items, entering a specific location, and you may even get one when completing a mission or even another Activity. Some Activities are like tutorials that push you to do something for the first time, and some come naturally when following the main story, etc.
Activities Include - "Speak To/With X Person", "Offer to help X Person", "Visit X Location", "Search for X In cave on X Planet", "Retrieve X", etc.
Specific Examples - "Visit your new penthouse in New Atlantis", "Visit the London Landmark on Earth", "Speak to Percival", "Use Hand Scanner to place an Outpost Beacon", "Craft or Modify an item", "Check out your ship's inventory", "Accept a Bounty Mission from the mission board".
You'll find that many activities involve speaking to someone, and speaking to said NPC is the activity itself. If you're traveling with a Companion, such as Sarah Morgan from Constellation, they'll occasionally have something to discuss with you. You'll then get the activity to speak with them.
Another way you'll receive an activity is by hearing an NPC talk out loud when you're near them or them talking directly to you. A very early one is when coming to New Atlantis, you can overhear a UC security officer talking about Sergeant Yumi looking for part-timers. You'll then get the activity "Talk to Sergeant Yumi", which will lead you to missions evolving security work.
I highly recommend talking to any named NPC you see (Some unnamed NPC's can be spoken to as well), as they may have a mission or activity to give. For example, when coming to New Atlantis for the first time, when using the NAT to reach the MAST district, you'll see an NCP named Donna Rain sweeping the floor. If you talk to her and accept her request, you'll receive the activity "Deliver a Terrabrew Cappuccino to Donna Rain"
Picking up Notes - Some vendors will have "Notes" that you can buy which will give you an activity that will involve going to a location to find an item or resource. Ex. - "Search for Plutonium in cave on Danra", or "Recover the Barrow Knife from Abandoned Muybridge"