Do you have any suggestions/tools to maintain self-discipline with exercise?

Sara D.
Remember why you started. Ask yourself, “why did I begin doing this? why do I want to keep doing this?” Really have time to reflect on the “why” of it all. Make sure you have time for it. Make time out of your day for it, it could even be just 30 minutes.
Ronald Z.
Don't fight your weaknesses, make them disappear. For example, don't fight to not open your phone when it's in front of you, just put it in another room and activate airplane mode.
Dev X.
I noticed that when I’m disciplined in one area…I carry the same attitude when looking at other areas of my life that I want to improve on