Stationary bike with automatic resistance and various apps to ride real routes or 3D ones with friends and family. I lost 2st last year without trying, which I gained during COVID. Now at 91% lean mass and in the shape of my life.

The key thing is finding people to be competitive and supportive with. My partner has been an excellent source of motivation as we are both very competitive in outdoing each other in time and power.

10 miles in an hour, do it a few times per week, you'll be on top of your self.