Stuck in a rut? I've been there, sister.
The best way out is to get an accountability buddy or set a big goal to work towards like say, a half or full marathon or perhaps a sprint triathlon. This is ideal for a fitness rut, but it really can apply to almost any stagnant area of your life!
If you have a twin or even a close sibling, the good news is you already have a great encouraging person alongside you. My hypothesis is having a twin makes you more competitive in general; growing up with someone literally vying for resources and attention translates to competing in school, sports, you name it. It's also a built-in cheerleader and all the other good stuff that pushes you to perform better and try new things.
Find that person in your life if you don't already have one. Maybe it's not your BFF, but your fitness or competition best friend. Seek out someone at your local running group, meet up group or recreational sports team. Find online groups or neighbors that like to run, swim, cycle; whatever! Having someone you can connect with and share similar values with (ideally fitness, lifestyle and nutrition) is the best way you push you to perform your best.
Using tools like a smart watch, training journal and food log like this Eat Pretty, Live Well can all push you to work harder and see areas of improvement. Reading fitness blogs (hello! That's what I'm here for) is a great first step. Having a buddy doing the same journey or process as you to compare notes and push each other is ideal for success, or at least a mentor or friend that will hold you accountable.
When I don't track (even loosely) my nutrition, I end up with waaay more snacking and treats than my body needs. When I don't track mileage and speed, I run waaay slower and shorter than I can. Every day of my marathon training I recorded my nutrition, workouts and moods. I'm confident this helped me finish, and not be nearly as sore as I thought I'd be!
My fave tools for success:
Granted, you can set and achieve goals solo, but knowing you have a support person or persons can be the key to getting you to work just that much harder. Having family cheering me on from near and far made a big difference at my first marathon, and seeing my twins just before mile 26 made me smile and push myself across that glorious finish line, whereas without those sweet and confused faces watching mama run, it would have been a slower (and sadder!) finish.
Having someone to share your trials and joy (and healthy energizing snacks) makes more an especially meaningful relationship. Whether it's a buddy, spouse, or kids, keep searching out that person. With so many online groups, fitness accounts, etc you can even find a remote buddy. I'm confident you can find someone to push and support you, and get your competitive side flowing.