diff --git a/scripts/run_simulation.jl b/scripts/run_simulation.jl
index 8bd6c69..af80c61 100644
--- a/scripts/run_simulation.jl
+++ b/scripts/run_simulation.jl
@@ -88,12 +88,11 @@ hm = Makie.heatmap!(ax, heat_obs, colormap=:viridis)
 ax.aspect = DataAspect()
 
 # # Controls
-
+run_label = Observable("Run")
 fig[2, 1] = buttongrid = GridLayout(tellwidth=false)
 btn_step = Button(buttongrid[1, 1], label="Step")
-btn_start = Button(buttongrid[1, 2], label="Start")
-btn_stop = Button(buttongrid[1, 3], label="Stop")
-btn_reset = Button(buttongrid[1, 4], label="Reset")
+btn_start = Button(buttongrid[1, 2], width=50, label=run_label)
+btn_reset = Button(buttongrid[1, 3], label="Reset")
 
 gh[1, 2] = textboxgrid = GridLayout(tellwidth=false)
 rowsize!(gh, 1, Relative(1.0))
@@ -134,29 +133,24 @@ function animation_loop()
         sleep(0.05)  # ~20 FPS
     end
 end
-on(box_u.stored_string) do s
-    try
-        Du[] = parse(Float64, s)
-        println("Change Du ", Du[])
-    catch
-        @warn "Invalid input for Du: $s"
+
+on(running) do r
+    run_label[] = r ? "Pause" : "Run"
     end
-end
+
 
 on(btn_step.clicks) do _
     multi_step!((U, V), 30)
 end
-
 on(btn_start.clicks) do _
-    if !running[]
-        running[] = true
-        @async animation_loop()
+    running[] = !running[]
+end
+on(btn_start.clicks) do _
+    @async while running[]
+        animation_loop()
     end
 end
 
-on(btn_stop.clicks) do _
-    running[] = false
-end
 
 on(btn_reset.clicks) do _
     running[] = false