Re: How to not get bored in The Sims 3/4?

@joaquito99 Oh, boy. I am up for this question! I also get easily bored if I just play one way, so I am continually challenging myself or finding new angles. I absolutely love the Sims, and part of why I love it is there are so many options...

If you are finding your Sims 4 a bit flat it is more my feeling that it CAN be played more simply, which works well for beginners and is preferred by many, but that is not all you can do. I will list just a few of the things that will 'spice up' your base game or your game play: (Please open 'spoiler tag' for my list of some things you can try to spice your game up a bit.)

• Purchase expansions. They can ad an incredible amount of interest and depth of possibilities for play, depending on the particular pack and what it adds. Some expansions even add careers, skills and a lot of interesting options.
• Enter challenges. On the forums you can find many threads with gameplay or build challenges that can be very challenging. This also provides potential for interaction with other players, etc.
• Collections. Many players love the challenge of completing collections.
• Careers. Play different careers.
• Change things up. I was surprised how much fun I had by downloading some households that others made that are talented in making interesting sims. I will tend to make mine more pleasant, and I run them in a rather 'Type A' manner. What about playing a slob in a household with /married to a neat sim? (A neat sim can be a handful also, as they are forever being uncomfortable with a mess. Or a Childish adult (like Clement Frost, who you will catch skipping around the house occasionally). A friend of mine said she played a clepto before and kept making them return the items. Anyway, there are some very interesting personality and interest combinations and career options. 
• Up your challenges in your households. If you play a large household, challenging career &/or financial goals, multiple households, out-of-household interaction/collection, etc. objectives it can increase your challenge level considerably.
• Buy / run a business.  This one overlaps the expansion suggestion. With Get To Work you gain careers plus you can go to work with some of them, and you can build/purchase/run a retail business. You can even sell goods that you make in the business, which increases the challenge also. (ie: Garden produce, food you cook/bake, paintings, items made on the Woodworking Table, etc. - you can sell most tings there, or items from build mode added to the store. With Dine Out you can eat out interactively or you can build/purchase and run/manage a restaurant. With Cats & Dogs you can build/purchase/run/be a vet at a veterinary clinic.
• Gardening challenges. This one overlaps the expansion suggestion also. With the Seasons Expansion you are able to add many features that switch things up, including weather, gardening seriously, joining the gardener (botanist or flower arranging/florist career) career.
• Expanding on the 'gardening challenges' suggestion... I like to have a cook & florist then have them also have a valuable garden and build a business for them where they sell the produce and cooked/baked goods in a retail store (through the Lice Cold Freezer customers can purchase directly from the freezer with no need to check them out) and make flower-arrangements to also sell in the store. (I have several stores set up to work this way in my gallery that you can download and use if yo udon't want to build one.)
• Build. Many gamers enjoy creating lots, rooms or households for uploading to the community gallery for others to download.
• Live differently.  Try starting off very poor or living as a homeless sim. Get Island Living and live off the grid. Forage for food/items to sell/ sing for tips, etc.

Anyway, this is just a beginning list. Many really cool options come with the various packs and expansions, though. That's just how Sims 4 is set up. The up side of this is that you can build your game as you can afford to add packs and you don't have to pay for feature you don't want to use. For instance, I gradually added packs and expansions in this way, and many of them I added when they went on sale (they cycle through putting various packs/expansions on sale and you can see if something is on sale when you start your game in Origin). I now own all of them, and I added them gradually in order of what featured things that I would enjoy most.